Preparation of building blocks for carba-oligosaccharides: Some protected 5a′-carba-D-hexopyranosyl-1,5-anhydro-2-deoxy-D-arabino-hex-1-enitols, and 5a,5a′-dicarba congeners thereof

Article abstract of DOI:10.1080/07328300600572907

Four configurational types of two protected O-linked (5a-carba-D- hexopyranosyl)-D-glucal and carba-D-glucal derivatives were prepared in order to provide versatile synthetic intermediates readily convertible into carba-oligosaccharides of biological inte

Full text of DOI:10.1080/07328300600572907

Journal of Carbohydrate Chemistry
ISSN: 0732-8303 (Print) 1532-2327 (Online) Journal homepage: http://www.tandfonline.com/loi/lcar20
Preparation of Building Blocks for
Carba‐Oligosaccharides: Some Protected
5a′‐Carba‐D‐hexopyranosyl‐1,5‐anhydro‐2‐deoxy‐D‐arabino‐he
and 5a,5a′‐Dicarba Congeners Thereof
Seiichiro Ogawa & Yoshiyuki Senba
To cite this article: Seiichiro Ogawa & Yoshiyuki Senba (2006) Preparation
of Building Blocks for Carba‐Oligosaccharides: Some Protected
5a′‐Carba‐D‐hexopyranosyl‐1,5‐anhydro‐2‐deoxy‐D‐arabino‐hex‐1‐enitols, and
5a,5a′‐Dicarba Congeners Thereof, Journal of Carbohydrate Chemistry, 25:1, 69-93, DOI:
10.1080/07328300600572907
To link to this article: http://dx.doi.org/10.1080/07328300600572907
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Date: 26 October 2015, At: 02:56

Journal of Carbohydrate Chemistry, 25:69–93, 2006
Copyright # Taylor & Francis Group, LLC
ISSN: 0732-8303 print 1532-2327 online
DOI: 10.1080/07328300600572907
Preparation of Building
Blocks for Carba-
Oligosaccharides: Some
Protected 5a0-Carba-D-
hexopyranosyl-1,5-anhydro-
2-deoxy-D-arabino-hex-1-
enitols, and 5a,5a0-Dicarba
Congeners Thereof
Seiichiro Ogawa and Yoshiyuki Senba
Department of Biosciences and Informatics, Faculty of Science and Engineering, Keio
University, Yokohama, Japan
Four configurational types of two protected O-linked (5a-carba-D-hexopyranosyl)-D-
glucal and carba-D-glucal derivatives were prepared in order to provide versatile
synthetic intermediates readily convertible into carba-oligosaccharides of biological
interest. These compounds may also find application as donors for elongation
of carba-oligosaccharide chains having O-linked carbahexopyranose residues at
nonreducing ends.
Keywords Carbohydrate mimics, Carbasugars, Carba-oligosaccharides, 5a0-Carba-
and 5a,5a0-dicarbadisaccharides, O-linked
INTRODUCTION
Recently, 5a-carbasugars[1–3] as well as N- and O-linked 5a0-carbadisaccharides
have been shown to act as substrate analogs[4–6] and/or inhibitors[7] for some
Received September 27, 2005; accepted January 5, 2006.
Address correspondence to Seiichiro Ogawa, Department of Biosciences and Infor-
matics, Faculty of Science and Engineering, Keio University, Hiyoshi, Kohoku-ku,
Yokohama, 223-8522 Japan. E-mail: sogawa379@ybb.ne.jp
69

S. Ogawa and Y. Senba
70
glycosyltransferases involved in oligosaccharide chain synthesis. Therefore,
taking advantage of these distinct features of carba-oligosaccharides, much
attention has been focused on the development of new glycosyltransferase
inhibitors.
There are three types of carba-disaccharides; taking carbacellobiose as an
example, type A is composed of two carbaglucopyranoses, and types B and C
consist of one carba- and one true-glucopyranoses (Fig. 1). In the present
study, versatile protected intermediates were prepared systematically,
aiming at provision of conventional sequences for design of biologically inter-
esting carba-oligosaccharides of types A and B, resistant to enzymatic hydroly-
sis. For strategic reasons the use of reactive D-glucal and carba-D-glucal as
precursors for reducing ends is desirable to minimize the crucial glycosylation
steps for elongation of oligosaccharide chains.
Attempts were made to prepare carba-disaccharides by allowing 1,2-
anhydro-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyranose[8] (1) to
couple with some protected glucal and carbaglucal derivatives 2–6 (Fig. 2).
Figure 1: Some protected 5a0-carba- and 5a,5a0-dicarba-disaccharide derivatives
synthesized in the present study.

Preparation of Building Blocks for Carba-Oligosaccharides
71
Figure 2: The 5a-carba-D-mannopyranosyl donor 1 and five acceptors 2–6.
The configurations of 5a-carba-a-D-mannopyranose residues in the obtained
condensates were then structurally modified through consecutive steps: first
oxidation of the 20-hydroxyl group, then base-catalyzed epimerization at C-10,
and finally selective reduction, to construct 5a-carba-a- and b-mannosyl and
a-and b-glucosyl-glucal derivatives. These protected compounds may find use
as acceptors or donors for chemical and/or biochemical preparation of
complex carba-oligosaccharides of biological interest.
RESULTS AND DISCUSSION
Preparation of 5a0-Carbadisaccharide Derivatives
First, 4- and 6-O-unprotected derivatives of D-glucal were chosen as accep-
tors for coupling. Thus, 3,6-di-O-benzyl-D-glucal (2) was prepared from
D-glucal under standard conditions.[9] Also 3,4-di-O-benzyl-D-glucal[10] (3)
was generated from 6-O-(tert-butyldiphenylsilyl)-D-glucal.
Coupling of the epoxide 1 (1.5 molar equiv) and the oxide anion generated
from compound 2 by treatment with an excess of NaH in dry DMF was carried
out in the presence of 15-crown-5 ether at 608C (Sch. 1). After treatment of the
reaction mixture with acetic anhydride in pyridine, a mixture of products was
easily separable by a silica gel column and the major product was isolated as
the O-acetyl derivative 8a (44%) in 87% yield based on 2 consumed. O-Deacyla-
tion of 8a with a catalytic amount of methanolic sodium methoxide in methanol
gave the alcohol 7a (97%), which was shown to be identical with the major
product observed in the coupling reaction mixture by TLC. The assigned
1
structure of 8a could be confirmed by H NMR spectroscopy: resonated broad
double doublets were present at d 4.09 and 4.17 for H-10 and H-20 with

S. Ogawa and Y. Senba
72
Scheme 1: Transformation of the coupled 7a–d into 5a0-carbadisaccharide derivatives
11a–d, 13a–d, and 15a–d: reagents and conditions: i) NaH, DMF, 15-crown-5 ether; 1 (1.5
molar equiv), acceptors 2 ꢀ 5, 608C (! 7a–d); Ac2O, pyridine, (! 8a–d); ii) NaOMe, MeOH;
Ac2O, DMSO, 258C; iii) DBU (1.5 molar equiv), toluene, 608C; iv) NaBH4, THF, 08C; v) CeCl.3. 7H2O,
MeOH, 08C; NaBH4, 08C.

Preparation of Building Blocks for Carba-Oligosaccharides
73
J ¼ ꢀ3.0 Hz, respectively. The alcohol 7a was then oxidized with acetic anhy-
dride in DMSO at 258C, giving the 2-keto derivative 9a (88%). Epimerization
of 9a (! 10a) was carried out under the influence of DBU (1.5 molar equiv)
in toluene at 608C. The equilibrium mixture of products was readily separated
on a silica gel column to give the anomer 10a (37%), together with 9a (54%).
Reduction of 9a with NaBH4 in THF at 08C produced the equatorial alcohol
11a (43%), together with 7a (28%). Compound 11a was then converted into
the O-acetyl derivative 12a (95%), the a-gluco configuration of which was
1
assigned by its H NMR spectrum: a doublet of double doublets was present
at d 4.32 for H-10 with J ¼ 2.0, 3.5, and 3.5 Hz.
On the other hand, treatment of 10a with cerium(III) chloride heptahy-
drate in methanol, followed by reduction with sodium borohydride at 08C,
gave, after separation on a silica gel column, the b-gluco and b-manno-carba-
disaccharides 13a (73%) and 15a (22%), which were further characterized as
the acetates 14a and 16a, respectively. Their assigned structures were con-
1
firmed on the basis of H NMR spectra: doublets of doublets appeared at d
5.00 and 5.64 for H-20 with J ¼ ꢀ9.5 and ꢀ3.0 Hz, respectively.
Secondly, the 6-O-unprotected D-glucal (3) was allowed to couple with the
epoxide 1 under similar conditions, affording a condensate 7b (56%), in 91%
yield based on 3 consumed, which was also converted into the acetate 8b.
The proposed structures were confirmed similarly on the basis of the 1H
NMR spectra. Oxidation of 7b with acetic anhydride in DMSO gave the
ketone 9b (94%), which underwent epimerization with DBU to afford an
approximately 1 : 1 mixture of products. This was fractionated by silica gel
chromatography to afford 9b (44%) and the anomer 10b (41%). A similar
reduction of 10b with NaBH4 gave the b-gluco and b-manno-type compounds
13b (39%) and 15b (56%), the structures of which were assigned on the basis
1
of the H NMR spectra of their O-acetyl derivatives 14b and 16b, containing
doublets of doublets at d 5.08 (J ¼ ꢀ9.4 Hz) and d 5.81 (J ¼ 2.7 and 2.9 Hz),
respectively.
Preparation of 5a,5a0-Dicarbadisaccharide Derivatives
1,5-Anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabino-hex-1-enitol[11]
(4) was chosen as a 3-OH free 5a-carba-D-glucal acceptor, and the other 4- and
6-O-unprotected derivatives were derivatized from 4. Thus, treatment of 4 with
benzyl bromide in DMF in the presence of NaH gave a crystalline benzyl ether
(90%), which was reduced with sodium cyanoborohydride in THF in the
presence of MS-4A at room temperature to produce, after separation through
a silica gel column, the 3,4- and 3,6-di-O-benzyl derivatives 5 (63%) and 6
(3%). The 1H NMR spectra of the respective O-acetyl derivatives, derived
from 5 and 6, revealed the downfield shifts (ꢀ1.4 and ꢀ0.6 ppm) of the
signals due to the protons attached to the carbon atoms bearing the acetoxyl

S. Ogawa and Y. Senba
74
groups. These data were likely to be related to those observed for the O-acetyl
derivatives of 2 and 3.
Coupling of the epoxide 1 with compound 4 was conducted under similar
conditions as described for 7a to give the a-mannopyranosyl 5a,5a0-dicarbadi-
saccharide derivative 7c (45%) in 66% yield based on 4 consumed. Under the
similar conditions, condensation of 1 with compound 5 gave 7d (17%) in 69%
yield based on 5 consumed. The structures of 7c and 7d were confirmed on
1
the basis of the respective acetyl derivatives 8c and 8d, the H NMR spectra
of which revealed the narrow signals at d 5.61 and 5.57 due to the equatorial
protons H-20 attached to the carbon atoms bearing the acetoxyl groups.
Attempted coupling of 1 with the 6-OH free carbaglucal 6, however, failed
under the standard conditions employed throughout in this study. The oxonium
ion generated from the primary hydroxyl group of 6 seems not to be stabilized
sufficiently (Fig. 3) to undergo nucleophilic attack of 6, compared to that of the
pyranoid congener 3, conceivably owing to a lack of the pyranoid oxygen atom
involved in favorable chelate formation.
Compound 7c,d could be transformed through a similar sequence of reac-
tions into the a,b-gluco- and b-manno-5a,5a0-dicarbadisaccharide derivatives
11c,d, 13c,d, and 15c,d, respectively. Thus, 7c was oxidized to the ketone 9c
(99%), which was subjected to the similar epimerization conditions to give
the epimer 10c (49%) and 9c (36%) recovered. Reduction of 10c with
NaBH4–CeCl3 in MeOH afforded the b-gluco and b-manno dicarbadisacchar-
ides 13c (50%) and 15c (43%). Their structures were confirmed on the basis
of 1H NMR spectra of the respective acetyl derivatives 14c and 16c, indicating
doublets of doublets (d 5.06, J ¼ 9.4 and 9.4 Hz) and (d 3.51, J ¼ 2.8 and 9.8 Hz)
due to H-20 and H-30, respectively.
On the other hand, 9c was reduced with NaBH4 in THF to give the a-gluco
dicarbadisaccharide 11c (64%) together with 7c (28%). The structure of 11c
was confirmed by the 1H NMR spectrum of its acetyl derivative 12c, which con-
tained the resonated signals due to H-20 and H-30 at d 4.87 (dd, J ¼ 3.3 and
9.9 Hz) and 4.08 (dd, J ¼ 9.4 and 9.9 Hz), respectively.
Compound 7d was oxidized to the ketone 9d (91%), which was subjected to
the similar epimerization conditions to give 9d (36%) and the epimer 10d
(46%). Reduction of 10d with NaBH4–CeCl3 in MeOH afforded the b-gluco
Figure 3: Postulated chelate formation of oxonium ions generated from compounds 3 and 6.

Preparation of Building Blocks for Carba-Oligosaccharides
75
and b-manno dicarbadisaccharides 13d (47%) and 15d (38%). Their structures
were confirmed on the basis of 1H NMR spectra of the respective acetyl deriva-
tives 14d and 16d, revealing doublets of doublets (d 5.02, J ¼ 9.4 and 9.4 Hz)
and (d 3.33, J ¼ 2.8 and 9.8 Hz) due to H-20 and H-30, respectively.
Reduction of 9c with NaBH4 in THF gave the a-gluco dicarbadisaccharide
11d, which was acetylated to the O-acetyl derivative 12d (53%) together with
8d (31%). The 1H NMR spectrum of 12d contained a signal due to H-20 at d 4.89
(dd, J ¼ 3.6 and 9.8 Hz), confirming the proposed structure.
1
Although H NMR spectra of the present dicarbadisaccharide derivatives
were shown to be rather complex, owing to an overlap of signals due to two
cyclitol moieties bonded by way of ether-linkage, the spectra could be interpreted
by correlation with those of a series of related carbadisaccharide derivatives.
CONCLUSION
Optimization of coupling reactions of epoxide and oxonium ions generated from
glucal and carbaglucal derivatives was not carried out in this study. Nucleophi-
licity of the oxonium ion may be controlled by the bulkiness of the molecule as
well as chemical features of the neighboring functions.[12] Among four acceptors
2–5 usable in the couplings, the oxonium ion generated from 5 was shown to be
the most inactive toward the epoxide 1, probably due to considerable steric hin-
drance. Also, concerning the crucial step of epimerization at the anomeric pos-
itions of carba-20-uronate residues of 9a–d, it appears that stereo-electronic
effects of the aglycon moieties, rather than combinations of both bases and
solvents, may influence the ratio of a/b-anomers in the range of 1 : 1–1 : 3.
In a synthesis of O-linked carba-oligosaccharides having carbasugar
moieties at non reducing ends, an important key step is construction of an
ether-linkage between a true sugar acceptor and a carbaglycosyl donor. There-
fore, desirable building blocks for synthesis of such carba-oligosaccharides may
include O-linked 5a0-carba-disaccharide derivatives with reactive glucal
residues at reducing ends. The 5a-carba- and 5a,5a0-dicarba-disaccharides
newly synthesized here can be readily transformed into 5a0-carba-a,b-
glucopyranosyl and b-mannopyranosylglucal derivatives, which can then be
chemically modified as well as biologically transformed into higher carba-
oligosaccharides of biological interest.
EXPERIMENTAL
General Procedures
Melting points: Mel-Temp capillary melting point apparatus, uncor-
rected. Specific rotations: Jasco DIP-370 polarimeter, 1-dm cells. IR

S. Ogawa and Y. Senba
76
spectra: Jasco A-202 or FT-IR-200. 1H NMR spectra: Jeol JNM GSX-270
f.t. (270 MHz) and Jeol Lambda-300 (300 MHz); solvent CDCl3 internal
standard tetramethylsilane (TMS), D2O external acetone. Mass spectra:
positive-ion electrospray ionization on a Jasco GC-Mass GC-Mare. TLC:
SilicaGel 60 GF (E. Merck, Darmstadt); detection by charring with concd
H2SO4. Column chromatography: silica gel 60 K070 (Katayama Chemicals,
Osaka), Wakogel C-33 (silica gel, 300 mesh, Wako Chemical, Osaka), and
Disogel sp-60 (silica gel, 60 mesh, Daiso, Osaka). Organic solutions, after
drying with anhydrous Na2SO4, were concentrated ,508C at diminished
pressure.
1,5-Anhydro-3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol (2). Accord-
ing to the standard procedure,[9] compound 2 was prepared from 3,4,6-tri-O-
acetyl-D-glucal in 66% yield as a syrup: [a]D26 –358 (c 1.2, CHCl3); ref.[9] [a]2D3
225.08 (c 5.7, CHCl3).
Acetylation of 2 (136 mg, 417 mmol) with acetic anhydride (0.7 mL) in
pyridine (1.4 mL) for 10 h at rt gave, after chromatography on a column of
silica gel (10 g, 1:10 ethyl acetate/hexane), the 4-O-acetyl derivative (154 mg,
1
ꢀ100%) as a syrup: [a]2D4 –198 (c 1.0, CHCl3); H NMR (300 MHz, CDCl3): d
6.45 (dd, 1H, J1,3 ¼ 1.2 Hz, J1,2 ¼ 6.2 Hz, H-1), 5.27 (dd, 1H, J3,4 ¼ 5.1 Hz,
J4,5 ¼ 10.1 Hz, H-4), 4.88 (ddd, 1H, J2,5 ¼ ꢀ1.0 Hz, J2,3 ¼ 3.9 Hz, J1,2 ¼ 6.2 Hz,
H-2), 4.61 and 4.54 (ABq, Jgem ¼ 12.2 Hz), and 4.56 and 4.50 (ABq,
Jgem ¼ 12.0 Hz) (2 ꢀ CH2Ph), 4.27 (dddd, 1H, J2,5 ¼ 1.0 Hz, J5,6b ¼ 4.4 Hz,
J5,6a ¼ 6.8 Hz, J4,5 ¼ 10.1 Hz, H-5), 3.93 (ddd, 1H, J1,3 ¼ 1.2 Hz, J2,3 ¼ 3.9 Hz,
J3,4 ¼ 5.1 Hz, H-3), 3.74 (dd, 1H, J5,6a ¼ 6.8 Hz, J6gem ¼ 10.6 Hz, H-6a), 3.64
(dd, 1H, J5,6b ¼ 4.4 Hz, J6gem ¼ 10.6 Hz, H-6b), 2.02 (s, 3H, Ac). Anal. Calcd for
C22H24O5: C, 71.72; H, 6.57. Found: C, 71.79; H, 6.64.
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-a-D-mannopyrano-
syl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol
(8a). To a stirred solution of 2 (33.4 mg, 102mmol) in DMF (0.50 mL) were
added in turn NaH (25 mg, 6 molar equiv) and 15-crown-5 ether (0.12 mL, 6
molar equiv) at an interval of 1 h at 08C. After stirring for a further 1 h, a
solution of 1,2-anhydro-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyr-
anose[8] (1) (52.0 mg, 1.5 molar equiv) in DMF (0.5mL) was added to the
mixture, and it was heated for 27 h at 608C. After the addition of a small
amount of MeOH, the reaction mixture was diluted with ethyl acetate
(30 mL), and the solution was thoroughly washed with water, dried (Na2SO4),
and evaporated. The residue was treated with acetic anhydride (0.5 mL) and
pyridine (1mL) overnight at rt. Evaporation of the excess reagents and the
products were purified by a column of silica gel (8g, 1:12 ! 1:5 ethyl acetate/
hexane, v/v) to give 8a [32 mg (44% yield), 87% based on 2 consumed] as a
1
syrup, along with 2 (16.5 mg) unchanged: [a]2D5 –238 (c 1.2, CHCl3); H NMR

Preparation of Building Blocks for Carba-Oligosaccharides
77
(300 MHz, CDCl3) (inter alia): d 7.52–7.12 (m, 20H, 4 ꢀ Ph), 6.40 (dd, 1H,
J4 ,5 ¼ 8.7 Hz, J3 ,4 ¼ 10.8 Hz, H-40), 5.60 (s, 1H, CHPh), 4.84 (dd, 1H,
J2,3 ¼ 2.1 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.64 and 4.54 (ABq, Jgem ¼ 11.7 Hz), and
0
0
0
0
4.51–4.60 (m, 4H) (3 ꢀ CH2Ph), 4.17 (br d, J1 ,2 ¼ ꢀ3 Hz, 1H, H-20), 4.09
0
0
(ddd, 1H, J1 ,5a ax ¼ 2.7 Hz, J1 ,2 ¼ ꢀ3 Hz, J1 ,5a eq ¼ 3.2 Hz, H-10), 4.07 (br dd,
0
0
0
0
0
0
0
0
1H, J1,3 ¼ 0.9 Hz, J2,3 ¼ 2.1 Hz, H-3), 4.01 (dd, 1H, J5 ,6 a ¼ 4.5 Hz,
J6 gem ¼ 11.1 Hz, H-60a), 3.71 (dd, 1H, J2 ,3 ¼ ꢀ3 Hz, J3 ,4 ¼ 10.8 Hz, H-30),
0
0
0
0
0
3.58 (dd, 1H, J6 gem ¼ 11.1 Hz, J5 ,6 b ¼ 12.0 Hz, H-60b), 2.47 (br s, 1H, OH),
0
0
0
0
0
0
0
0
0
2.14 (ddddd, 1H, J5 ,5a eq
¼
3.2 Hz, J5 ,6 a ¼ 4.5 Hz, J4 ,5 ¼ 8.7 Hz,
J5 ,6 b ¼ 12.0 Hz, J5 ,5a ax ¼ 12.5 Hz, H-50), 1.53 (ddd, 1H, J1 ,5a eq
¼
0
0
0
0
0 0
J5 ,5a eq ¼ 3.2 Hz, J5a gem ¼ 13.8 Hz, H-5a0eq), 1.22 (ddd, 1H, J1 ,5a ax ¼ 2.7 Hz,
0
0
0
0
0
J5 ,5a ax ¼ 12.5 Hz, J5a gem ¼ 13.8 Hz, H-5a0ax). Anal. Calcd for C43H46O9: C,
0
0
0
73.07; H, 6.56. Found: C, 73.02; H, 6.59.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-mannopyranosyl-(1 ! 4)-
3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol (7a). A solution of 8a
(24.3 mg, 34 mmol) in MeOH (1.0 mL) was treated with 1 M methanolic
sodium methoxide (0.2 mL) for 8 h at rt. After neutralization with Amberlite
IR-120 (Hþ) resin and evaporation, the product was purified by chromato-
graphy on silica gel (3 g, 1:5 ethyl acetate/hexane, v/v) to give 7a (22 mg,
1
97%) as a syrup: [a]2D6 –238 (c 1.1, CHCl3); H NMR (300 MHz, CDCl3) (inter
alia): d 7.52–7.21 (m, 20H, 4 ꢀPh), 6.40 (dd, 1H, J1,3 ¼ 0.9 Hz, J1,2 ¼ 6.1 Hz,
H-1), 5.60 (s, 1H, CHPh), 4.84 (dd, 1H, J2,3 ¼ 2.1 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.75
and 4.51 (ABq, Jgem ¼ 11.7 Hz), and 4.62–4.47 (m, 4 H) (3 ꢀ CH2Ph), 4.17 (br
dd, 1H, J2 ,3 ¼ 2.9 Hz, J1 ,2 ¼ 3.2 Hz, H-20), 4.09 (ddd, 2H, J1 ,5a ax ¼ 2.6 Hz,
0
0
0
0
0
0
J1 ,2 ¼ J1 ,5a eq ¼ 3.2 Hz, H-10), 4.01 (dd, 1H, J5 ,6 a ¼ 4.5 Hz, J6 gem ¼ 11.0 Hz,
0
0
0
0
0
0
0
H-60a), 3.58 (dd, 1H, J5 ,6 b ¼ J6 gem ¼ 11.0 Hz, H-60b), 2.47 (br s, 1H, OH),
0
0
0
0
0
0
0
0
0
0
0
2.14 (ddddd, 1H, J5 ,5a eq ¼ 3.2 Hz, J5 ,6 a ¼ 4.5 Hz, J4 .5 ¼ 8.7 Hz, J5 ,6 b
¼
12.0 Hz, J5 ,5a ax ¼ 12.5 Hz, H-50), 1.46 (dd, 1H, J1 ,5a eq ¼ J5 ,5a eq ¼ 3.2 Hz,
0
0
0
0
0
0
H-5a0eq), 1.38 (ddd, 1H, J1 ,5a ax ¼ 2.6 Hz, J5 ,5a ax ¼ 12.5 Hz, J5a gem
¼
0
0
0
0
0
13.5 Hz, H-5a0ax). Anal. Calcd for C41H44O8: C, 74.08; H, 6.67. Found C,
74.28; H, 6.73.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-arabino-hex-2-ulopyranos-
yl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol
(9a). To a solution of 7a (93.7 mg, 141 mmol) in DMSO (3.0 mL) was added acetic
anhydride (0.40 mL, 30 molar equiv), and it was stirred for 10 h at 258C. After
treatment with a small amount of methanol, the mixture was diluted with
ethyl acetate (100 mL), and the solution was washed thoroughly with water,
dried, and evaporated. The product was purified by chromatography (silica
gel: 12 g, 1:19 ethyl acetate/toluene, v/v) to give 9a (82.3 mg, 88%) as a syrup:
[a]2D5 –588 (c 0.28, CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 7.60–7.16
(m, 20H, 4 ꢀ Ph), 6.39 (dd, 1H, J1,3 ¼ 1.2 Hz, J1,2 ¼ 6.1 Hz, H-1), 5.55 (s, 1H,

S. Ogawa and Y. Senba
78
CHPh), 4.77 (dd, 1H, J2,3 ¼ 2.7 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.66 and 4.46 (ABq,
Jgem ¼ 12.0 Hz), 4.63 and 4.54 (ABq, Jgem ¼ 12.0 Hz), and 4.41 and 4.35 (ABq,
0
0
0
0
Jgem ¼ 11.5 Hz) (3 ꢀ CH2Ph), 4.20 (dd, 1H, J1 ,5a ax ¼ 2.7 Hz, J1 ,5a eq ¼ 3.2 Hz,
H-10), 4.14 (dd, 1H, J5 ,6 a ¼ 4.4 Hz, J6 gem ¼ 11.0 Hz, H-60a), 4.08 (ddd, 1H,
0
0
0
0
0
J1,3 ¼ 1.2 Hz, J2,3 ¼ 2.7 Hz, J3,4 ¼ 8.5 Hz, H-3), 1.75 (ddd, 1H, J1 ,5a eq ¼ 3.2 Hz,
J5 ,5a eq ¼ 3.4 Hz, J5a gem ¼ 14.4 Hz, H-5a0eq), 1.12 (ddd, 1H, J1 ,5a ax ¼ 2.7 Hz,
0
0
0
0
0
J5 ,5a ax ¼ 13.2 Hz, J5a gem ¼ 14.4 Hz, H-5a0ax). Anal. Calcd for C41H42O8: C,
0
0
0
74.30; H, 6.39. Found: C, 74.21; H, 6.40.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-arabino-hex-2-ulopyrano-
syl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol
(10a). To a solution of 9a (35.0 mg, 52.8 mmol) in toluene (1.4 mL) was added
DBU (12 mL, 1.5 molar equiv), and it was stirred for 8 h at 608C. The mixture
was then diluted with ethyl acetate (50 mL), and the solution was washed
thoroughly with water, dried (Na2SO4), and evaporated. The products were
chromatographed on silica gel (5 g, 1:20 ethyl acetate/toluene, v/v) to give 9a
(16 mg, 54%), along with 10a (13 mg, 37%), as crystals: mp 123–1248C; [a]D25
–258 (c 0.65, CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 7.51–7.23
(m, 20H, 4 ꢀ Ph), 6.43 (br d, 1H, J1,2 ¼ 6.1 Hz, H-1), 5.50 (s, 1H, CHPh), 4.87
(dd, 1H, J2,3 ¼ 2.0 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.82 and 4.55 (ABq,
Jgem ¼ 12.2 Hz), 4.61 and 4.54 (ABq, Jgem ¼ 12.0 Hz,), and 4.66 and 4.40
(ABq, Jgem ¼ 12.0 Hz) (3 ꢀ CH2Ph), 4.34 (m, 1H, H-10), 4.24 (dd, 1H,
J2,3 ¼ 2.0 Hz, J3,4 ¼ 7.1 Hz, H-3), 3.92 (d, 1H, J3 ,4 ¼ 10.1 Hz, H-30), 3.78 (dd,
0
0
0
0
1H, J3,4 ¼ 7.1 Hz, J4,5 ¼ 9.5 Hz, H-4), 1.12 (ddd, 1H, J1 ,5a ax ¼ 12.6 Hz,
J5 ,5a ax ¼ 12.9 Hz, J5a gem ¼ 13.4 Hz, H-5a0ax). Anal. Calcd for C41H42O8: C,
0
0
0
74.30; H, 6.39. Found: C, 74.18; H, 6.41.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-glucopyranosyl-(1 ! 4)-1,
5-anhydro-3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol (11a). To a
solution of 9a (13.0 mg, 19.6 mmol) in THF (1.0 mL) was added sodium borohy-
dride (2.2 mg, 3 molar equiv), and it was stirred for 25 h at 08C. The mixture
was diluted with ethyl acetate (20 mL), and the solution was washed with
water, dried (Na2SO4), and evaporated. The products were separated by
preparative TLC (silica gel) with (2:3 ethyl acetate/hexane, v/v), 7a (3.7 mg,
1
28%) and 11a (5.6 mg, 43%) as syrups: [a]1D9 –118 (c 0.28, CHCl3); H NMR
(300 MHz, CDCl3) (inter alia): d 7.53–7.22 (m, 20H, 4 ꢀ Ph), 6.40 (dd, 1H,
J1,3 ¼ 1.0 Hz, J1,2 ¼ 5.1 Hz, H-1), 5.55 (s, 1H, CHPh), 4.85 (dd, 1H,
J2,3 ¼ 2.4 Hz, J1,2 ¼ 6.11 Hz, H-2), 4.68–4.58 (m, 4 H) and 4.78 and
4.53 (ABq, Jgem ¼ 11.2 Hz) (3 ꢀ CH2Ph), 4.25 (br ddd, 1H, J1,3 ¼ J2,3
¼
¼
0
0
0
0
0
0
ꢀ2.4 Hz, J3,4 ¼ 6.8 Hz, H-3), 4.19 (ddd, 1H, J1 ,5a ax ¼ 2.0 Hz, J1 ,2 ¼ J1 ,5a eq
2.5 Hz, H-10), 1.58 (ddd, 1H, J1 ,5a eq ¼ ꢀ2.5 Hz, J5 ,5a eq ¼ 3.4 Hz,
0
0
0
0
J5a gem ¼ 14.2 Hz, H-5a0eq), 0.90 (ddd, 1H, J1 ,5a ax ¼ 2.0 Hz, J5 ,5a ax¼12.9 Hz,
0
0
0
0
0
J5a gem ¼ 14.2 Hz, H-5a0ax).
0

Preparation of Building Blocks for Carba-Oligosaccharides
79
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-a-D-glucopyranos-
yl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol
(12a). Compound 11a (5.4 mg, 8.1 mmol) was acetylated with acetic anhydride
and pyridine in the usual manner to give, after chromatography (silica gel: 2 g,
1:15 ethyl acetate/toluene, v/v) to give 12a (5.4 mg, 95%) as a syrup: [a]2D1 –68
1
(c 0.27, CHCl3); H NMR (300 MHz, CDCl3) (inter alia): d 7.46–7.17 (m, 20H,
4 ꢀ Ph), 6.38 (br d, 1H, J1,2 ¼ 6.1 Hz, H-1), 5.51 (s, 1H, CHPh), 4.84 and 4.58
(ABq, Jgem ¼ 11.7H), 4.55 and 4.48 (ABq, Jgem ¼ 12.0 Hz), and 4.46 and 4.36
0
0
0
0
(ABq, Jgem ¼ 11.2 Hz) (3 ꢀ CH2Ph), 4.32 (br ddd, 1H, J1 ,5a ax ¼ 2.0 Hz, J1 ,2
¼
J1 ,5a eq ¼ 3.5 Hz, H-10), 3.65 (dd, 1H, J5,6a ¼ 3.2 Hz, J6gem ¼ 10.7 Hz, H-6a),
0
0
3.54 (dd, 1H, J3 ,4 ¼ 9.5 Hz, J4 ,5 ¼ 10.3 Hz, H-40), 3.48 (dd, 1H, J5 ,6 a
¼
0
0
0
0
0
0
J6 gem ¼ 11.0 Hz, H-60a), 1.93 (s, 3H, Ac), 1.74 (ddd, 1H, J1 ,5a eq ¼ 2.0 Hz,
0
0
0
J5 ,5a eq ¼ ꢀ3.5 Hz, J5a gem ¼ 14.2 Hz, H-5a0eq), 0.84 (ddd, 1H, J1 ,5a ax
¼
0
0
0
0
0
2.0 Hz, J5 ,5a ax ¼ 12.5 Hz, J5a gem ¼ 14.2 Hz, H-5a0ax). Anal. Calcd for
0
0
0
C43H46O9: C, 73.07; H, 6.56. Found: C, 72.71; H, 6.59.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-glucopyranosyl-(1 ! 4)-1,5-
anhydro-3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol (13a) and 3-O-
Benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyranosyl-(1 ! 4)-1,5-
anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-hex-1-enitol (15a).
A solution of 10a (12.7 mg, 19.2 mmol) and cerium(III) chloride heptahydrate
(0.10 g, 14 molar equiv) in methanol (0.50 mL) was stirred for 30 min at 08C.
Sodium borohydride (10 mg, 14 molar equiv) was added to the mixture, which
was then stirred for 47 h at 08C. The mixture was diluted with ethyl acetate
(50 mL), and the solution was washed with water, dried (Na2SO4), and evapor-
ated. The residue was chromatographed on silica gel (2g, 1:15 ethyl acetate/
toluene, v/v) to give 13a (8.7 mg, 73%) and 15a (2.8 mg, 22%) as a syrup:
1
13a: m.p. 116–1188C; [a]2D8 –288 (c 0.44, CHCl3); H NMR (300 MHz, CDCl3)
(inter alia): d 7.50–7.24 (m, 20H, 4 ꢀ Ph), 6.40 (dd, 1H, J1,3 ¼ 1.2 Hz,
J1,2 ¼ 6.1 Hz, H-1), 5.51 (s, 1H, CHPh), 4.89 (dd, 1H, J2,3 ¼ 2.4 Hz,
J1,2 ¼ 6.1 Hz, H-2), 4.94 and 4.76 (ABq, Jgem ¼ 11.5 Hz), 4.66 and 4.60 (ABq,
Jgem ¼ 12.0 Hz), and 4.70 and 4.43 (ABq, Jgem ¼ 11.5 Hz) (3 ꢀ CH2Ph), 4.14
(m, 1H, H-3), 3.97 (br d, 1H, J6gem ¼ 11.2 Hz, H-6a), 3.79 (dd, 1H,
J5,6b ¼ 2.0 Hz, J6gem ¼ 11.2 Hz, H-6b), 3.68 (m, 1H, H-10), 1.74 (ddd, 1H,
J1 ,5a eq ¼ 4.9 Hz, J1 ,5a ax ¼ 11.2 Hz, J5a gem ¼ 12.8 Hz, H-5a0eq), 0.92 (ddd,
0
0
0
0
0
1H, J1 ,5a ax ¼ J5 ,5a ax ¼ 11.2 Hz, J5a gem ¼ 12.8 Hz, H-5a0ax).
0
0
0
0
0
1
15a: [a]1D9 þ88 (c 0.3, CHCl3); H NMR (300 MHz, CDCl3) (inter alia): d 7.51–
7.28 (m, 20H, 4 ꢀ Ph), 6.41 (dd, 1H, J1,3 ¼ 1.2 Hz, J1,2 ¼ 6.1 Hz, H-1), 5.57
(s, 1H, CHPh), 4.89 (dd, 1H, J2,3 ¼ 2.0 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.69 and 4.65
(ABq, Jgem ¼ 12.3 Hz), 4.67–4.54 (m, 2 H), and 4.66 and 4.45 (ABq,
Jgem ¼ 11.5 Hz) (3 ꢀ CH2Ph), 4.30 (br s, 1H, H-20), 4.23 (dd, 1H, J2,3 ¼ 2.0 Hz,

S. Ogawa and Y. Senba
80
J3,4 ¼ 7.1 Hz, H-3), 3.59 (dd, 1H, J5 ,6 a ¼ J6 gem ¼ 10.7 Hz, H-60a), 3.32 (dd, 1H,
0
0
0
J2 ,3 ¼ 3.0 Hz, J3 ,4 ¼ 9.5 Hz, H-30), 2.78 (br s, 1H, OH).
0
0
0
0
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-glucopyranos-
yl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol
(14a). Compound 13a (8.3 mg, 12.5 mmol) was acetylated conventionally to
give, after chromatography (silica gel: 2 g, 1:10 ethyl acetate/toluene, v/v),
1
14a (8.6 mg, 98%) as a syrup: [a]2D7 –88 (c 0.5, CHCl3); H NMR (300 MHz,
CDCl3) (inter alia): d 7.50–7.22 (m, 20H, 4 ꢀ Ph), 6.39 (dd, 1H, J1,3 ¼ 1.2 Hz.
0
0
0
0
J1,2 ¼ 6.1 Hz, H-1), 5.52 (s, 1H, CHPh), 5.00 (t, 1H, J1 ,2 ¼ J2 ,3 ¼ 9.5 Hz,
H-20), 4.86 (dd, 1H, J2,3 ¼ 2.9 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.89 and 4.58 (ABq,
Jgem ¼ 12.0 Hz), 4.64 and 4.44 (ABq, Jgem ¼ 12.5 Hz), and 4.58 and 4.51
(ABq, Jgem ¼ 12.0 Hz) (3 ꢀ CH2Ph), 3.65–3.55 (m, 1H, H-10), 1.88 (m, 1H,
J5 ,5a eq ¼ 3.4 Hz, J1 ,5a eq ¼ 4.4 Hz, J5a gem ¼ 13.2 Hz, H-5a0eq), 0.98 (ddd, 1H,
0
0
0
0
0
J1 ,5a ax ¼ 11.7 Hz, J5 ,5a ax ¼ 12.9 Hz, J5a gem ¼ 13.2 Hz, H-5a0ax). Anal. Calcd
0
0
0
0
0
for C43H46O9: C, 73.07; H, 6.56. Found: C, 72.74; H, 6.65.
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-b-D-mannopyranosyl-(1 ! 4)
-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-hex-1-enitol
(16a). Compound 15a (6.0 mg, 9.0 mmol) was acetylated conventionally to give,
after chromatography (silica gel: 2 g, 1:10 ethyl acetate/toluene, v/v), 16a
(6.3 mg, 98%) as a syrup: [a]D19 –248 (c 0.25, CHCl3); 1H NMR (300 MHz,
CDCl3) (inter alia): d 7.44–7.14 (m, 20H, 4 ꢀ Ph), 6.35 (dd, 1H, H-1), 5.64
(m, 1H, J2 ,3 ¼ 2.9 Hz, H-20), 5.48 (s, 1H, CHPh), 4.82 (dd, 1H, J2,3 ¼ 2.4 Hz,
J1,2 ¼ 6.1 Hz, H-2), 4.60 and 4.36 (ABq, Jgem ¼ 11.2 Hz), 4.58–4.51 (m, 2 H),
and 4.58 and 4.36 (ABq, Jgem ¼ 12.9 Hz) (3 ꢀ CH2Ph), 3.86 (dd, 1H,
0
0
J5 ,6 a ¼ 3.9 Hz, J6 gem ¼ 10.6 Hz, H-60a), 3.80–3.60 (m, 1H, H-10), 3.50 (dd,
0
0
0
1H, J5 ,6 b ¼ 10.5 Hz, J6 gem ¼ 10.6 Hz, H-60b), 3.25 (dd, 1H, J2 ,3 ¼ 2.9 Hz,
0
0
0
0
0
J3 ,4 ¼ 9.5 Hz, H-30), 2.02 (s, 3H, Ac), 1.57 (ddd, 1H, J1 ,5a eq ¼ 2.7 Hz,
0
0
0
0
J5 ,5a eq ¼ 3.2 Hz, J5a gem ¼ 11.8 Hz, H-5a0eq). Anal. Calcd for C43H46O9: C,
0
0
0
73.07; H, 6.56. Found: C, 72.55; H, 6.79.
1,5-Anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol
(3).
According to the standard procedure,[10] compound 3 was prepared: syrup, Rf
0.3 (1:3 acetone/hexane); [a]2D6 –418 (c 1.20, CHCl3); ref.[10] [a]2D0 –34.88 (c
0.82, CHCl3).
For further characterization, the acetyl derivative was obtained in the
usual manner: syrup, Rf 0.46 (1:3 acetone/hexane); [a]2D8 þ2.48 (c 1.10,
1
CHCl3); H NMR (300 MHz, CDCl3): d 7.37–7.25 (m, 10 H, Ph), 6.39 (br dd,
1H, J1,3 ¼ 1.0 Hz, J1,2 ¼ 6.1 Hz, H-1), 4.92 (dd, 1H, J2,3 ¼ 2.7 Hz,
J1,2 ¼ 6.1 Hz, H-2), 4.85 and 4.66 (ABq, Jgem ¼ 11.2 Hz), and 4.66 and 4.56
(ABq, Jgem ¼ 11.4 Hz) (2 ꢀ CH2Ph), 4.41 (dd, 1H, J5,6a ¼ 2.9 Hz, Jgem
¼
12.2 Hz, H-6a), 4.35 (dd, 1H, J5,6b ¼ 5.1 Hz, Jgem ¼ 12.2 Hz, H-6b), 4.23 (br

Preparation of Building Blocks for Carba-Oligosaccharides
81
ddd, 1H, J1,3 ¼ 1.0 Hz, J2,3 ¼ 2.7 Hz, J3,4 ¼ 6.1 Hz, H-3), 4.09 (ddd, 1H,
J5,6a ¼ 2.9 Hz, J5,6b ¼ 5.1 Hz, J4,5 ¼ 8.5 Hz, H-5), 3.77 (dd, 1H, J3,4 ¼ 6.1 Hz,
J4,5 ¼ 8.5 Hz, H-4), 2.05 (s, 3H, Ac). Anal. Calcd for C22H24O5: C, 71.72; H,
6.57. Found: C, 71.53; H, 6.78.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-mannopyranosyl-(1 ! 6)-
1,5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol (7b).
Coupling of 1 (125 mg, 370 mmol, 1.5 molar equiv) and 3 (80.2 mg, 246 mmol)
was carried out similarly as in the preparation of 7a. The products were chro-
matographed on silica gel (50 g, 1:30 ethyl acetate/toluene, v/v) to give 7b
[91.5 mg (56% yield), 91% based on 3 consumed], along with 3 (30.5 mg)
1
unchanged: [a]2D6 þ158 (c 0.88, CHCl3); H NMR (300 MHz, CDCl3): d 7.53–
7.21 (m, 20H, 4 ꢀ Ph), 6.35 (dd, 1H, J1,3 ¼ 1.2 Hz, J1,2 ¼ 6.1 Hz, H-1), 5.61
(s, 1H, CHPh), 4.87 (br dd, J2,3 ¼ 2.4 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.85 and 4.65
(ABq, Jgem ¼ 11.2 Hz), 4.68 and 4.56 (ABq, Jgem ¼ 11.7 Hz), and 4.63 (m, 2 H)
(3 ꢀ CH2Ph), 4.21 (ddd, 1H, J1,3 ¼ 1.2 Hz, J2,3 ¼ 2.4 Hz, J3,4 ¼ 6.1 Hz, H-3),
4.16 (br dd, 1H, J ¼ ꢀ2.9 Hz, H-20), 4.07 (dd, 1H, J5 ,6 a ¼ 4.4 Hz,
0
0
J6 gem ¼ 11.0 Hz, H-60a), 3.74 (br ddd, 1H, J ¼ ꢀ2.5 Hz, H-10), 3.67 (dd, 1H,
0
0
0
0
J5,6a ¼ 2.7 Hz, J6gem ¼ 10.8 Hz, H-6a), 3.64 (dd, 1H, J5 ,6 b ¼ J6 gem ¼ 11.0 Hz,
H-6b0), 2.56 (br s, 1H, OH), 2.21 (m, 1H, H-50), 1.44 (br ddd, 1H,
J1,5a ax ¼ ꢀ3 Hz, J5 ,5a ax ¼ J5a gem ¼ ꢀ13 Hz, H-5a0ax).
0
0
0
0
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-a-D-mannopyrano-
syl-(1 ! 6)-1,5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-en-
itol (8b). Compound 7b (17.6 mg, 27mmol) was acetylated as in the preparation
of 8a. The product was purified by chromatography on silica gel (2g, 1:9 ethyl
acetate/toluene, v/v) to give 8b (17.5 mg, 94%) as a syrup: [a]1D9 þ168 (c 0.87,
1
CHCl3); H NMR (300 MHz, CDCl3): d 7.47–7.12 (m, 20H, 4 ꢀ Ph), 6.25 (dd,
1H, J1,3 ¼ 1.2 Hz, J1,2 ¼ 6.1 Hz, H-1), 5.56 (br s, 1H, CHPh), 5.49 (br t, 1H,
J ¼ ꢀ2.0 Hz, H-20), 4.79 (dd, 1H, J2,3 ¼ 2.7 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.76 and
4.56 (ABq, Jgem ¼ 11.1 Hz), 4.60 (s, 2 H), and 4.58 and 4.49 (ABq,
Jgem ¼ 11.7 Hz) (3 ꢀ CH2Ph), 4.13 (br dd, 1H, J2,3 ¼ 2.4 Hz, J3,4 ¼ 6.3 Hz, H-3),
4.01 (dd, 1H, J5 ,6 a ¼ 4.5 Hz, J6 gem ¼ 11.0 Hz, H-60a), 3.70 (dd, 1H,
J3,4 ¼ 6.3 Hz, J4,5 ¼ 8.4 Hz, H-4), 3.66 (dd, 1H, J5,6a ¼ 2.4 Hz, J6gem ¼ 10.5 Hz,
0
0
0
H-6a), 3.57 (t, 1H, J5 ,6 b ¼ J6 gem ¼ 11.0 Hz, H-60b), 3.56 (ddd, 1H, J ¼ ꢀ2.0 Hz,
0
0
0
H-10), 2.04 (s, 3H, OAc), 1.51 (ddd, 1H, J1 ,5a eq ¼ J5 ,5a eq ¼ ꢀ2.0 Hz,
0
0
0
0
J5a gem ¼ 13.8 Hz, H-5a0eq), 1.27 (ddd, 1H, J1 ,5a ax
¼
2.5 Hz, J5 ,5a ax
¼
0
0
0
0
0
J5a gem ¼ 13.8 Hz, H-5a0ax). Anal. Calcd for C43H46O9: C, 73.07; H, 6.56.
0
Found: C, 73.01; H, 6.69.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-arabino-hex-2-ulopyrano-
syl-(1 ! 6)-1,5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-en-
itol (9b). Compound 7b (57.2 mg, 86 mmol) was treated with acetic anhydride

S. Ogawa and Y. Senba
82
(0.25 mL, 30 molar equiv) in DMSO (1.7 mL) for 15 h at 258C. After usual
processing, the product was purified by column chromatography (silica gel:
10 g, 1:15 ethyl acetate/toluene, v/v) to give 9b (53.7 mg, 94%) as crystals:
1
mp 123–1248C; [a]2D4 þ158 (c 1.0, CHCl3); H NMR (300 MHz, CDCl3) (inter
alia): d 7.48–7.12 (m, 20H, 4 ꢀ Ph), 6.12 (dd, 1H, J1,3 ¼ 1.2 Hz, J1,2 ¼ 6.1 Hz,
H-1), 5.48 (s, 1H, CHPh), 4.79 (m, 1H, H-2), 4.59 (m, 1H, H-30), 4.78 and 4.57
(ABq, Jgem ¼ 11.2 Hz), 4.74 and 4.56 (ABq, Jgem ¼ 11.4 Hz), and 4.58 and 4.48
0
0
(ABq, Jgem ¼ 11.5 Hz) (3 ꢀ CH2Ph), 4.15 (dd, 1H, J5 ,6 a ¼ 4.4 Hz,
J6 gem ¼ 11.0 Hz, H-60a), 4.12 (m, 1H, H-3), 3.82–3.74 (m, 1H, H-10), 2.56
0
0
0
0
0
0
0
0
0
(ddddd, 1H, J5 ,5a eq ¼ 3.4 Hz, J5 ,6 b ¼ 4.4 Hz, J4 ,5 ¼ J5 ,6 a ¼ ꢀ10.5 Hz,
J5 ,5a ax ¼ 13.2 Hz, H-50), 1.81 (ddd, 1H, J1 ,5a eq ¼ 3.2 Hz, J5 ,5a eq ¼ 3.4 Hz,
0
0
0
0
0
0
J5a gem ¼ 14.5 Hz, H-5a0eq), 1.18 (ddd, 1H, J1 ,5a ax ¼ 2.7 Hz, J5 ,5a ax
¼
0
0
0
0
0
13.2 Hz, J5a gem ¼ 14.5 Hz, H-5a0ax). Anal. Calcd for C41H42O8: C, 74.30; H,
0
6.39. Found: C, 74.24; H, 6.45.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-arabino-hex-2-ulopyrano-
syl-(1 ! 6)-1,5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-en-
itol (10b). Compound 9b (50.7 mg, 76.5 mmol) was treated with DBU (17 mL,
1.5 molar equiv) in toluene (2.0 mL) for 7 h at 608C. After usual processing,
the product was purified by silica gel chromatography (10 g, 1:20 ethyl
acetate/toluene, v/v) to give 9b (22 mg, 44%) and 10b (26.3 mg, 41%): [a]D22
–
10.48 (c 0.78, CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 7.52–7.25
(m, 20H, 4 ꢀ Ph), 6.39 (d, 1H, J1,2 ¼ 6.1 Hz, H-1), 5.55 (s, 1H, CHPh), 4.89 (br d,
1H, J1,2 ¼ 6.1 Hz, H-2), 4.91 and 4.66 (ABq, Jgem ¼ 12.3 Hz), 4.89 and 4.80 (ABq,
Jgem ¼ 12.1 Hz), and 4.64 and 4.54 (ABq, Jgem ¼ 11.5 Hz) (3 ꢀ CH2Ph), 4.11–
3.96 (m, 2H, H-5, H-10), 4.06 (d, 1H, J3 ,4 ¼ 10.0 Hz, H-30), 3.84–3.77 (m, 1H,
0
0
H-10), 1.27 (ddd, 1H, J5 ,5a ax ¼ 12.0 Hz, J1 ,5a ax ¼ 12.5 Hz, J5a gem ¼ 12.6 Hz,
0
0
0
0
0
H-5a0ax). Anal. Calcd for C41H42O8: C, 74.30; H, 6.39. Found: C, 74.29; H, 6.42.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-glucopyranosyl-(1 ! 6)-1,
5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol
(11b).
Compound 9b (13.1 mg, 19.8 mmol) was treated with NaBH4 (2.2 mg, 3 molar
equiv) in THF at 08C as in the preparation of 11a. The products were chromato-
graphed on silica gel (3 g, 1:15 ethyl acetate/toluene, v/v), to give 7b (4.2 mg,
1
32%) and 11b (8.7 mg, 66%) as a syrup: [a]2D2 þ318 (c 0.32, CHCl3); H NMR
(300 MHz, CDCl3):
d
7.53–7.20 (m, 20H, 4 ꢀ Ph), 6.39 (br d, 1H,
J1,2 ¼ 6.3 Hz, H-1), 5.57 (s, 1H, CHPh), 4.90 (br dd, 1H, J2,3 ¼ 3.0 Hz,
J1,2 ¼ 6.3 Hz, H-2), 4.96 and 4.78 (ABq, Jgem ¼ 11.4 Hz), 4.85 and 4.65 (ABq,
Jgem ¼ 11.4 Hz), and 4.60 (m, 2 H) (3 ꢀ CH2Ph), 4.09 (dd, 1H, J5,6a ¼ 4.2 Hz,
J6gem ¼ 10.5 Hz, H-6a), 3.94 (dd, 1H, J5,6b ¼ 5.1 Hz, J6gem ¼ 10.5 Hz, H-6b),
3.58 (dd, 1H, J3 ,4 ¼ J4 ,5 ¼ 11.0 Hz, H-40), 2.83 (d, 1H, J2 ,OH ¼ 7.5 Hz, OH),
0
0
0
0
0
1.73 (ddd, 1H, J1 ,5a eq ¼ J5 ,5a eq ¼ 3.0 Hz, J5a gem ¼ 14.4 Hz, H-5a0eq), 1.01 (br
0
0
0
0
0
t, 1H, J1 ,5a ax ¼ ꢀ3 Hz, J5 ,5a ax ¼ 13.5 Hz, J5a gem ¼ 14.4 Hz, H-5a0ax).
0
0
0
0
0

Preparation of Building Blocks for Carba-Oligosaccharides
83
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-a-D-glucopyranos-
yl-(1 ! 6)-1,5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol
(12b). Compound 11b (6.4 mg, 9.6 mmol) was acetylated as in the preparation of
12a to give, after chromatography (silica gel, 2 g, 1:15 ethyl acetate/toluene, v/
1
v) to give 12b (6.7 mg, 99%) as a syrup: [a]2D2 þ218 (c 0.34, CHCl3); H NMR
(300 MHz, CDCl3) (inter alia): d 7.53–7.19 (m, 20H, 4 ꢀ Ph), 6.35 (br dd, 1H,
J1,3 ¼ 1.0 Hz, J1,2 ¼ 6.0 Hz, H-1), 5.59 (s, 1H, CHPh), 4.89 and 4.85 (ABq,
each 1H, Jgem ¼ 11.0 Hz, CH2Ph), 4.88 (dd, 1H, J2,3 ¼ 2.7 Hz, J1,2 ¼ 6.0 Hz,
H-2), 4.80 (dd, 1H, J1 ,2 ¼ 3.0 Hz, J2 ,3 ¼ 10.0 Hz, H-20), 4.19 (br dd, 1H,
J1,3 ¼ 1.0 Hz, J2,3 ¼ 2.7 Hz, J3,4 ¼ 5.7 Hz, H-3), 3.89 (dd, 1H, J3,4 ¼ 5.7 Hz,
0
0
0
0
J4,5 ¼ 8.4 Hz, H-4), 4.01 (dd, 1H, J2 ,3 ¼ J3 ,4 ¼ ꢀ10 Hz, H-30) 3.64 (br dd, 1H,
0
0
0
0
J3 ,4 ¼ J4 ,5 ¼ ꢀ11.0 Hz, H-40), 2.01 (s, 3H, Ac), 1.74 (ddd, 1H, J1 ,5a eq
¼
0
0
0
0
0
0
J5 ,5a eq ¼ 3.5 Hz, J5a gem ¼ 14.0 Hz, H-5a0eq), 1.07 (ddd, 1H, J1 ,5a ax ¼ 1.5 Hz,
0
0
0
0
0
J5 ,5a ax ¼ 13.5 Hz, J5a gem ¼ 14.0 Hz, H-5a0ax). Anal. Calcd for C43H46O9: C,
0
0
0
73.07; H, 6.56. Found: C, 72.93; H, 6.80.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-glucopyranosyl-(1 ! 6)-1,
5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol (13b) and
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyranosyl-(1 ! 6)-
1,5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-enitol (15b).
Compound 10b (11.7 mg, 17.7 mmol) was treated with sodium borohydride in
the presence of cerium(III) chloride in methanol as in the preparation of 13a
and 15a. The products were chromatographed on silica gel (2 g, 1:15 ethyl
acetate/toluene, v/v) to give 13b (4.6 mg, 39%) and 15b (6.5 mg, 56%) as syrups.
13b: [a]2D2 –3.48 (c 0.23, CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 7.51–
7.29 (m, 20H, 4 ꢀ Ph), 6.41 (dd, 1H, J1,3 ¼ 0.7 Hz, J1,2 ¼ 6.1 Hz, H-1), 5.56 (s, 1H,
CHPh), 4.88 (dd, 1H, J2,3 ¼ 2.9 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.99 and 4.77 (ABq,
Jgem ¼ 11.4 Hz), 4.85 and 4.73 (ABq, Jgem ¼ 11.2 Hz), and 4.64 and 4.55 (ABq,
Jgem ¼ 11.7 Hz) (3 ꢀ CH2Ph), 4.19 (dd, 1H, J2,3 ¼ 2.9 Hz, J3,4 ¼ 6.1 Hz, H-3),
4.14 (dd, 1H, J5 6 a ¼ 4.4 Hz, J6 gem ¼ 11.1 Hz, H-60a), 4.03 (ddd, 1H,
J5,6a ¼ 3.4 Hz, J5,6b ¼ 5.1 Hz, J4,5 ¼ 8.3 Hz, H-5), 3.81 (dd, 1H, J3,4 ¼ 6.1 Hz,
0
0
0
J4,5 ¼ 8.3 Hz, H-4), 3.34 (br d, 1H, J1 ,2 ¼ 10.5 Hz, H-10), 2.83 (br s, 1H, OH),
0
0
1.00 (ddd, 1H, J1 ,5a ax ¼ 11.2 Hz, J5 ,5a ax ¼ 12.9 Hz, J5a gem ¼ 13.2 Hz, H-5a0ax).
0
0
0
0
0
15b: [a]2D3 þ248 (c 0.25, CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 7.48–
7.25 (m, 20H, 4 ꢀ Ph), 6.36 (dd, 1H, J1,3 ¼ 1.0 Hz, J1,2 ¼ 6.1 Hz, H-1), 5.56
(s, 1H, CHPh), 4.86 (dd, 1H, J2,3 ¼ 2.9 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.81 and 4.71
(ABq, Jgem ¼ 12.3 Hz), 4.79 and 4.65 (ABq, Jgem ¼ 11.6 Hz), and 4.59 and
0
0
4.48 (ABq, Jgem ¼ 11.7 Hz) (3 ꢀ CH2Ph), 4.24 (br dd, 1H, J1 ,2 ¼ 2.2 Hz,
J2 ,3 ¼ 2.8 Hz, H-20), 3.63 (dd, 1H, J5 ,6 a ¼ 10.6 Hz, J6 gem ¼ 10.7 Hz, H-60a),
0
0
0
0
0
3.39 (dd, 1H, J2 ,3 ¼ 2.8 Hz, J3 ,4 ¼ 9.6 Hz, H-30), 3.30 (m, 1H, J1 ,2 ¼ 2.2 Hz,
0
0
0
0
0
0
J1 ,5a eq ¼ 6.6 Hz, J1 ,5a ax ¼ 9.3 Hz, H-10), 2.43 (br s, 1H, OH).
0
0
0
0

S. Ogawa and Y. Senba
84
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-glucopyranos-
yl-(1 ! 6)-1,5-anhydro-3,4-di-O-benzyl-2-deoxy-5a-carba-D-arabino-hex
-1-enitol (14b). Compound 13b (4.6 mg, 6.9 mmol) was acetylated as in the
preparation of 13a to give, after chromatography (silica gel: 2 g, 1:10 ethyl
acetate/toluene, v/v), 14b (4.9 mg, 100%) as a syrup: [a]1D9 þ118 (c 0.25,
CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 7.53–7.23 (m, 20H,
4 ꢀ Ph), 6.38 (br d, 1H, J1,2 ¼ 6.0 Hz, H-1), 5.56 (s, 1H, CHPh), 5.08 (dd, 1H,
J1 ,2 ¼ J2 ,3 ¼ 9.4 Hz, H-20), 4.88 (dd, 1H, J2,3 ¼ 3.0 Hz, J1,2 ¼ 6.0 Hz, H-2),
0
0
0
0
4.13 (dd, 1H, J5 ,6 eq ¼ 4.0 Hz, J6 gem ¼ 10.8 Hz, H-6a0eq), 4.12 (dd, 1H,
J2,3 ¼ 3.0 Hz, J3,4 ¼ 7.5 Hz, H-3), 3.98 (ddd, 1H, J ¼ ꢀ4.0 Hz, H-5), 3.65 (dd,
0
0
0
1H, J3 ,4 ¼ J4 ,5 ¼ 9.4 Hz, H-40), 3.60 (dd, 1H, J5 ,6 ax ¼ J6 gem ¼ 10.8 Hz,
0
0
0
0
0
0
0
H-60ax), 3.55 (dd, 1H, J3 ,4 ¼ 9.0 Hz, J2 ,3 ¼ 9.4 Hz, H-30), 3.41 (ddd, 1H,
0
0
0
0
J1 ,5a eq ¼ 4.5 Hz, J1 ,2 ¼ 10.5 Hz, J1 ,5a ax ¼ 10.8 Hz, H-10), 1.95 (s, 3H, Ac),
0
0
0
0
0
0
1.81 (ddd, 1H, J1 ,5a eq ¼ J5 ,5a eq ¼ 3.0 Hz, J5a gem ¼ 12.7 Hz, H-5a0eq), 1.72
0
0
0
0
0
(m, 1H, H-50), 1.04 (ddd, 1H, J5 ,5a ax ¼ 11.4 Hz, J1 ,5a ax ¼ 12.0 Hz, J5a gem
¼
0
0
0
0
0
12.7 Hz, H-5a0ax).
HRMS Calcd for C43H46O9. Found: 706.2947 (M: 0.1%).
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyrano-
syl-(1 ! 6)-1,5-anhydro-3,4-di-O-benzyl-2-deoxy-D-arabino-hex-1-en-
itol (16b). Compound 15b (5.5 mg, 8.3 mmol) was acetylated as in the prep-
aration of 12a to give, after chromatography (silica gel: 2 g, 1:10 EtOAc/
1
toluene, v/v), 16b (5.4 mg, 93%) as a syrup: [a]2D2 –8.68 (c 0.27, CHCl3); H
NMR (300 MHz, CDCl3): d 7.53–7.28 (m, 20H, 4 ꢀ Ph), 6.38 (dd, 1H,
0
0
0
0
J1,3 ¼ 1.0 Hz, J1,2 ¼ 6.1 Hz, H-1), 5.81 (dd, 1H, J1 ,2 ¼ 2.7 Hz, J2 ,3 ¼ 2.9 Hz,
H-20), 5.60 (s, 1H, CHPh), 4.89 (dd, 1H, J2,3 ¼ 2.9 Hz, J1,2 ¼ 6.1 Hz, H-2), 4.83
and 4.69 (ABq, Jgem ¼ 11.5 Hz), 4.70 and 4.67 (ABq, Jgem ¼ 10.4 Hz), and
4.63 and 4.53 (ABq, Jgem ¼ 11.6 Hz) (3 ꢀ CH2Ph), 4.16 (dd, 1H, J2,3 ¼ 2.9 Hz,
J3,4 ¼ 5.7 Hz, H-3), 4.12 (dd, 1H, J5 ,6 a ¼ 4.3 Hz, J6 gem ¼ 10.9 Hz, H-60a), 4.02
0
0
0
0
0
(dd, 1H, J5,6b ¼ 3.6 Hz, J5,6a ¼ 5.4 Hz, H-5), 3.89 (dd, 1H, J3 ,4 ¼ 9.8 Hz,
J4 ,5 ¼ 10.0 Hz, H-40), 3.86 (dd, 1H, J5,6a ¼ 5.4 Hz, J6gem ¼ 11.1 Hz, H-6a),
3.78 (dd, 1H, J3,4 ¼ 5.7 Hz, J4,5 ¼ 8.1 Hz, H-4), 3.72 (dd, 1H, J5,6b ¼ 3.6 Hz,
0
0
J6gem ¼ 11.1 Hz, H-6b), 3.67 (t, 1H, J5 ,6 b ¼ J6 gem ¼ 10.9 Hz, H-60b), 3.48 (dd,
0
0
0
1H, J2 ,3 ¼ 2.9 Hz, J3 ,4 ¼ 9.8 Hz, H-30), 3.44 (br ddd, 1H, J1 ,2 ¼ 2.7 Hz,
0
0
0
0
0
0
J1 ,5a eq ¼ 4.5 Hz, J1 ,5a ax ¼ 11.4 Hz, H-10), 2.11 (s, 3H, Ac). Anal. Calcd for
0
0
0
0
C43H46O9: C, 73.07; H, 6.56. Found: C, 72.65; H, 6.77.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyranosyl-(1 ! 3)-
1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabino-hex-1-en-
itol (7c): A mixture of 1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-
arabino-hex-1-enitol[11] (4, 195 mg, 0.84 mmol) in DMF (3.0 mL) was treated
with NaH (100 mg, 3 molar equiv) for 1 h at 08C to rt. To the mixture was
added 15-crown-5 ether (0.50 mL, 3 molar equiv), and it was stirred for 1 h at

Preparation of Building Blocks for Carba-Oligosaccharides
85
08C to rt. After addition of the epoxide 1 (426 mg, 1.5 molar equiv), it was
stirred for 16 h at 608C. The reaction was quenched by addition of methanol,
the reaction mixture was diluted with EtOAc, and the solution was washed
with water, dried, and evaporated. The residue was chromatographed on a
column of silica gel (100 g, 1:30 EtOAc/toluene) to give 7c [216 mg (45%
yield), 66%] as a syrup: Rf 0.5 (1:3 EtOAc/toluene); [a]2D2 –678 (c 0.80,
CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 7.46–7.12 (m, 15 H,
3 ꢀ Ph), 5.68 (m, 1H, J1,3 ¼ J1,5a(ax) ¼ 2.4 Hz, J1,5a(eq) ¼ 4.8 Hz, J1,2
¼
10.2 Hz, H-1), 5.53 (br s, 2H, 2 ꢀ CHPh), 5.51 (br d, 1H, J1,2 ¼ 10.5 Hz, H-2),
0
0
4.49 and 4.20 (ABq, Jgem ¼ 11.5 Hz, CH2Ph), 4.06 (dd, 1H, J5 ,6 a ¼ 4.4 Hz,
J6 gem ¼ 11.0 Hz, H-60a), 3.96 (m, 1H, J1 ,5a eq ¼ 2.7 Hz, J1 ,5a ax ¼ 5.6 Hz, H-10),
0
0
0
0
0
3.86 (dd, 1H, J3 ,4 ¼ 9.5 Hz, J4 ,5 ¼ 10.2 Hz, H-40), 3.77 (dd, 1H, J2 ,3
¼
0
0
0
0
0
0
3.2 Hz, J3 ,4 ¼ 9.5 Hz, H-30), 2.46 (br s, 1H, OH), 2.23 (m, 1H, H-50), 2.08
(dddd, 1H, J5,5a(eq) ¼ J5,6a ¼ ꢀ5 Hz, J5,5a(ax) ¼ J5,6b ¼ ꢀ11 Hz, H-5), 1.96 [ddd,
1H, J1,5a(eq) ¼ J5,5a(eq) ¼ ꢀ5.0 Hz, J5agem ¼ 17.2 Hz, H-5a(eq)], 1.68 [ddddd,
0
0
1H, J2,5a(ax) ¼ J5a(ax),6a ¼ J5a(ax),6b ¼ 2.8 Hz, J5,5a(ax) ¼ 11.2 Hz, J5agem
17.2 Hz, H-5a(ax)] 1.50–1.44 (m, 2H, 2 ꢀ H-5a0).
¼
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-glucopyranos-
yl-(1 ! 3)-1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (8c): Compound 7c (16 mg, 29 mmol) was acetylated in the usual
manner and the product was chromatographed on a column of silica gel (2 g, 1:9
EtOAc/toluene) to give 8c (17 mg, 97%) as a syrup: Rf 0.57 (1:4 EtOAc/toluene);
[a]2D0 –528 (c 0.88, CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 7.52–7.12
(m, 15 H, 3 ꢀ Ph), 5.75 (m, 1H, J1,3 ¼ 1.5 Hz, J1,5a(ax) ¼ 2.2 Hz, J1,5a(eq)
¼
2.4 Hz, J1,2 ¼ 10.3 Hz, H-1), 5.62 and 5.61 (2 s, each 1H, 2 ꢀ CHPh), 5.61
(m, 1H, H-20), 5.54 (m, 1H, J1,2 ¼ 10.3 Hz, H-2), 4.30–4.22 (m, 3H, H-3,
CH2Ph), 4.19 (dd, 1H, J5,6a ¼ 4.9 Hz, J6gem ¼ 11.2 Hz, H-6a), 4.13 (dd, 1H,
J5 ,6 a ¼ 4.4 Hz, J6 gem ¼ 10.8 Hz, H-60a), 3.97 (m, 1H, H-10), 3.77 (dd, 1H,
0
0
0
0
0
0
J3,4 ¼ 7.8 Hz, J4,5 ¼ 11.0 Hz, H-4), 3.67 (dd, 1H, J5 ,6 b ¼ 6.9 Hz, J6 gem
¼
10.8 Hz, H-60b), 3.64 (dd, 1H, J5,6b ¼ 6.9 Hz, J6gem ¼ 11.2 Hz, H-6b), 2.17 [m,
1H, J5,6a ¼ 4.9 Hz, J5,5a(eq) ¼ 5.1 Hz, J4,5 ¼ 11.0 Hz, J5,6b ¼ 11.2 Hz, H-5], 2.04
[m, 1H, H-5a(eq)], 2.06 (s, 3H, Ac), 1.75 [m, 1H, H-5a(ax)], 1.60 (m, 1H,
H-5a0eq), 1.40 (ddd, 1H, J1 ,5a ax ¼ 2.7 Hz, J5 ,5a ax ¼ 13.4 Hz, J5a gem
¼
0
0
0
0
0
13.7 Hz, H-5a0ax). Anal. Calcd for C37H40O8: C, 72.53; H, 6.58. Found: C,
72.36; H, 6.76.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-arabino-hex-2-ulopyrano-
syl-(1 ! 3)-1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabi-
no-hex-1-enitol (9c): A solution of 7d (82 mg, 143 mmol) in DMSO (2.5 mL)
was treated with acetic anhydride (0.41 mL, 30 molar equiv) for 15 h at rt.
After addition of methanol, the mixture was diluted with EtOAc, and the
solution was washed thoroughly with water, dried (Na2SO4), and evaporated.

S. Ogawa and Y. Senba
86
The residue was chromatographed on a column of silica gel (10 g, 1:10 EtOAc/
toluene) to give 9d (81 mg, 99%) as a crystalline solid: [a]2D2 –648 (c 0.65,
1
CHCl3); H NMR (300 MHz, CDCl3): d 7.46–7.08 (m, 15 H, 3 ꢀ Ph), 5.73 (dd,
1H, J1,3 ¼ J1,5a(ax) ¼ ꢀ2.0 Hz, J1,5a(eq) ¼ 4.8 Hz, J1,2 ¼ 10.0 Hz, H-1), 5.57 (dd,
1H, J2,3 ¼ 2.7 Hz, J1,2 ¼ 10.0 Hz, H-2), 5.56 and 5.47 (2 s, each 1H,
2 ꢀ CHPh), 4.79 and 3.51 (ABq, Jgem ¼ 10.0 Hz, CH2Ph), 3.97 (ddd, 1H,
0
0
J1,3 ¼ 2.0 Hz, J2,3 ¼ 2.7 Hz, J3,4 ¼ 7.8 Hz, H-3), 3.80 (d, 1H, J3 ,4 ¼ 11.2 Hz,
H-30), 3.70 (dd, 1H, J3,4 ¼ 7.8 Hz, J4,5 ¼ 10.7 Hz, H-4), 1.87 (ddd, 1H, J1 ,5a eq
¼
0
0
J5 ,5a eq ¼ 3.4 Hz, J5a gem ¼ 14.3 Hz, H-5a0eq), 1.23 (ddd, 1H, J1 ,5a ax ¼ 2.4 Hz,
0
0
0
0
0
J5 ,5a ax ¼ 13.4 Hz, J5a gem ¼ 14.3 Hz, H-5a0ax). Anal. Calcd for C35H36O7: C,
0
0
0
73.92; H, 6.38. Found: C, 73.72; H, 6.45.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-arabino-hex-2-ulopyrano-
syl-(1 ! 3)-1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabi-
no-hex-1-enitol (10c): A solution of 9c (68 mg, 120 mmol) in toluene (2.7 mL)
was treated with DBU (27 mL, 1.5 molar equiv) for 3 h at 608C. The mixture
was then diluted with EtOAc, and the solution was washed with water, dried
(Na2SO4), and evaporated. The residue was chromatographed on a column of
silica gel (20 g, 1:15 EtOAc/toluene) to give 10c (33 mg, 64%) as crystals: Rf
0.6 (1:3 EtOAc/tolurne); [a]D24 –15.58 (c 1.23, CHCl3); 1H NMR (300 MHz,
CDCl3) (inter alia): d 7.45–7.08 (m, 15H, 3 ꢀ Ph), 5.86 (br d, 1H,
J1,2 ¼ 10.0 Hz, H-2), 5.69 (m, 1H, J1,3 ¼ J1,5a(ax) ¼ 2.5 Hz, J1,5a(eq) ¼ 4.8 Hz,
J1,2 ¼ 10.0 Hz, H-1), 5.54 and 5.47 (2 s, each 1H, 2 ꢀ CHPh), 4.82 and 4.55
0
0
0
0
(ABq, Jgem ¼ 12.2 Hz, CH2Ph), 4.45 (br dd, 1H, J1 ,5a eq ¼ 6.5 Hz, J1 ,5a ax
¼
12.6 Hz, H-10), 3.78 (dd, 1H, J3,4 ¼ 7.8 Hz, J4,5 ¼ 10.9 Hz, H-4), 1.25 (ddd, 1H,
J1 ,5a ax ¼ J5 ,5a ax ¼ 12.6 Hz, J5a gem ¼ 12.9 Hz, H-5a0ax). Anal. Calcd for
0
0
0
0
0
C35H36O7: C, 73.92; H, 6.38. Found: C, 73.63; H, 6.56.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-glucopyranosyl-(1 ! 3)-1,
5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabino-hex-1-enito
l (11c). A solution of compound 10c (56 mg, 98 mmol) in THF (1.0 mL) was
treated with NaBH4 (19 mg, 5 molar equiv) for 3 h at 08C. After the addition
of a small amount of H2O, the mixture was diluted with EtOAc and the
solution was washed with H2O, dried, and evaporated. The residual product
was chromatographed on a column of silica gel (10 g, 1 : 15 EtOAc/toluene) to
give 11c (36 mg, 64%) as crystals, along with 7d (16 mg, 28%): Rf 0.34 (1:3
EtOAc/toluene); mp 202.5–2048C; [a]2D3 –658 (c 1.8, CHCl3); 1H NMR
(300 MHz, CDCl3) (inter alia): d 7.55–7.21 (m, 15 H, 3 ꢀ Ph), 5.73 (m, 1H,
J1,3 ¼ J1,5a(ax) ¼ ꢀ2 Hz, J1,5a(eq) ¼ 4.8 Hz, J1,2 ¼ 10 Hz, H-1), 5.65 (s, 1H,
CHPh), 5.58 (br d, 1H, J1,2 ¼ 10 Hz, H-2), 5.56 (s, 1H, CHPh), 4.61 and 4.40
(ABq, Jgem ¼ 11.2 Hz, CH2Ph), 4.43 (br dd, 1H, J1,3 ¼ 2.4 Hz, J3,4 ¼ 8.2 Hz,
H-3), 4.17 (dd, 1H, J5 ,6 a ¼ 4.4 Hz, J6 gem ¼ 11.2 Hz, H-60a), 3.88 (dd, 1H,
0
0
0
J3,4 ¼ 8.2 Hz, J4,5 ¼ 10.7 Hz, H-4), 3.69 (dd, 1H, J5,6a ¼ 10.7 Hz, J6gem
¼

Preparation of Building Blocks for Carba-Oligosaccharides
87
0
0
0
0
0
11.4 Hz, H-6a), 1.13 (ddd, 1H, J5 ,5a ax ¼ 13.2 Hz, J1 ,5a ax ¼ 13.7 Hz, J5a gem
¼
13.9 Hz, H-5a0ax).
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-a-D-glucopyranos-
yl-(1 ! 3)-1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (12c). Compound 11c (36 mg, 63 mmol) was acetylated in the
usual manner, and the product was chromatographed on a column of silica
gel (4 g, 1:10 EtOAc/toluene) to give 12c (39 mg, ꢀ100%) as crystals: mp
1
172–1738C; [a]2D4 –308 (c 1.9, CHCl3); H NMR (300 MHz, CDCl3) (inter alia):
d 7.53–7.22 (m, 15 H, 3 ꢀ Ph), 5.76 (br dd, 1H, J1,3 ¼ 2.4 Hz, J1,2 ¼ 10.0 Hz,
H-1), 5.61 and 5.60 (2 s, each 1H, 2 ꢀ CHPh), 5.55 (br d, 1H, J1,2 ¼ 10.0 Hz,
H-2), 4.87 (dd, 1H, J1 ,2 ¼ 3.3 Hz, J2 ,3 ¼ 9.9 Hz, H-20), 4.89 and 4.63 (ABq,
0
0
0
0
Jgem ¼ 11.7 Hz, CH2Ph), 4.08 (dd, 1H, J3 ,4 ¼ 9.4 Hz, J2 ,3 ¼ 9.9 Hz, H-30),
3.86 (dd, 1H, J3,4 ¼ 7.8 Hz, J4,5 ¼ 10.7 Hz, H-4), 1.83 (s, 3H, Ac), 1.78 (ddd,
0
0
0
0
1H, J1 ,5a eq ¼ J5 ,5a ax ¼ 3.4 Hz, J5a gem ¼ 13.8 Hz, H-5a0eq), 1.14 (ddd, 1H,
0
0
0
0
0
J1 ,5a ax ¼ 3.0 Hz, J5 ,5a ax ¼ 12.6 Hz, J5a gem ¼ 13.8 Hz, H-5a0ax). Anal. Calcd
0
0
0
0
0
for C37H40O8: C, 72.53; H, 6.58. Found: C, 72.17; H, 6.77.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-glucopyranosyl-(1 ! 3)-1,
5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabino-hex-1-en-
itol (13c) and 3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyr-
anosyl-(1 ! 3)-1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-ara-
bino-hex-1-enitol (15c). Compound 10d (17.4 mg, 30.6 mmol) was reduced
with NaBH4 in the presence of cerium(III) chloride as in the preparation of
13a and 15a. The products were chromatographed on silica gel (4 g, ethyl
acetate/toluene, 1:10, v/v) to give 13c (6.7 mg, 39%) and 15c (5.7 mg, 33%),
along with 10c (4 mg) unchanged.
13c: mp 201–202.58C; [a]2D1 –378 (c 0.33, CHCl3); 1H NMR (300 MHz, CDCl3): d
7.51–7.23 (m, 15 H, 3 ꢀ Ph), 5.75 (ddd, 1H, J1,3 ¼ 2.0 Hz, J1,5a(eq) ¼ 4.4 Hz,
J1,2 ¼ 10.3 Hz, H-1), 5.70 (br d, 1H, J1,2 ¼ 10.3 Hz, H-2), 5.62 and 5.56 (2 s,
each 1H, 2 ꢀ CHPh), 4.98 and 4.75 (ABq, Jgem ¼ 11.4 Hz, CH2Ph), 4.21 (ddd,
1H, J1,3 ¼ 2.0 Hz, J2,3 ¼ 3.4 Hz J3,4 ¼ 8.1 Hz, H-3), 4.20 (dd, 1H,
0
0
0
J5,6a ¼ 4.4 Hz, J6gem ¼ 11.0 Hz, H-6a), 4.08 (dd, 1H, J5 ,6 a ¼ 4.6 Hz, J6 gem
¼
11.1 Hz, H-60a), 3.76 (dd, 1H, J3,4 ¼ 8.1 Hz, J4,5 ¼ 11.0 Hz, H-4), 3.68 (dd, 1H,
0
J6gem ¼ 11.0 Hz, J5,6b ¼ 11.5 Hz, H-6b), 3.60 (dd, 1H, J6 gem ¼ 11.1 Hz,
J5 ,6 b ¼ 11.2 Hz, H-60b), 2.82 (br s, 1H, OH), 2,15 (ddddd, 1H,
J5,5eq ¼ J5,6a ¼ ꢀ4.5 Hz, J4,5 ¼ J5,5ax ¼ J5,6b ¼ ꢀ11 Hz, H-5), 1.95 (ddd, 1H,
0
0
J1 ,5a eq ¼ J5 ,5a eq ¼ ꢀ3.5 Hz, J5a gem ¼ 13.0 Hz, H-5a0eq).
0
0
0
0
0
15c: [a]2D1 þ5.68 (c 0.36, CHCl3); 1H NMR (300 MHz, CDCl3): d 7.52–7.27 (m, 15
H, 3 ꢀ Ph), 5.75 (ddd, 1H, J1,3 ¼ J1,5a(ax) ¼ 2.0 Hz, J1,5aeq ¼ 4.5 Hz,
J1,2 ¼ 10.2 Hz, H-1), 5.62 and 5.60 (2 s, each 1H, 2 ꢀ CHPh), 5.57 (br s, 1H,

S. Ogawa and Y. Senba
88
0
0
H-2), 4.85 and 4.73 (ABq, Jgem ¼ 12.1 Hz, CH2Ph), 4.35 (dd, 1H, J1 ,2 ¼ 2.4 Hz,
J2 ,3 ¼ 2.6 Hz, H-20), 4.25 (ddd, 1H, J1,3 ¼ 2.0 Hz, J2,3 ¼ 4.0 Hz, J3,4 ¼ 7.8 Hz,
H-3), 4.20 (dd, 1H, J5,6a ¼ 4.5 Hz, J6gem ¼ 11.0 Hz, H-6a), 4.08 (dd, 1H,
0
0
J5 ,6 a ¼ 3.3 Hz, J6 gem ¼ 11 Hz, H-6a0), 4.05 (dd, 1H, J3 ,4 ¼ J4 ,5 ¼ 9.5 Hz,
H-40), 3.81 (m, 1H, J3,4 ¼ 7.8 Hz, J4,5 ¼ 11.0 Hz, H-4), 3.77 (m, 1H,
0
0
0
0
0
0
0
J1 ,2 ¼ 2.4 Hz, H-10), 3.67 (dd, 1H, J5 ,6 b ¼ J6 gem ¼ ꢀ11 Hz, H-60b), 3.47 (dd,
0
0
0
0
0
1H,J2 ,3 ¼ 2.6 Hz,J3 ,4 ¼ 9.5 Hz,H-30),2.51(brs,1H,OH),2.15(ddddd,1H,J5,6a ꢀ5 Hz,
J5,6a ¼ ꢀ5 Hz, J5,5a(eq) ¼ 5.1 Hz, J4,5 ¼ J5,5a(ax) ¼ J5,6b ¼ ꢀ9 Hz, H-5), 2.04
[ddd, 1H, J1,5a(eq) ¼ 4.4 Hz, J5,5a(eq) ¼ 5.1 Hz, J5agem ¼ 11.5 Hz, H-5a(eq)].
0
0
0
0
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-glucopyranos-
yl-(1 ! 3)-1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (14c). Compound 13c (6.7 mg, 12 mmol) was acetylated and
purified as in the preparation of 14a to give 14c (7.0 mg, 97%) as crystals:
mp 199.5–200.58C; [a]2D1 –108 (c 0.36, CHCl3); 1H NMR (300 MHz, CDCl3)
(inter alia): d 7.51–7.26 (m, 15 H, 3 ꢀ Ph), 5.45 (br d, 1H, J1,2 ¼ 10.0 Hz,
H-1), 5.06 (t, 1H, J1 ,2 ¼ J2 ,3 ¼ 9.4 Hz, H-20), 4.89 and 4.64 (ABq,
Jgem ¼ 11.7 Hz, CH2Ph), 4.15 (br dd, 1H, J1,3 ¼ 2.2 Hz, J3,4 ¼ 8.4 Hz, H-3),
0
0
0
0
4.04 (dd, 1H, J5 ,6 a ¼ 4.4 Hz, J6 gem ¼ 11.0 Hz, H-60a), 3.60 (t, 1H, J5 ,6 b
¼
0
0
0
0
0
J6 gem ¼ 11.0 Hz, H-60b), 3.52 (t, 1H, J2 ,3 ¼ J3 ,4 ¼ 9.4 Hz, H-30), 2.00 (s, 3H,
0
0
0
0
0
0
0
0
0
0
Ac), 1.16 (ddd, 1H, J1 ,5a eq ¼ 11.4 Hz, J1 ,5a ax ¼ 12.7 Hz, J5a gem ¼ 12.8 Hz,
H-5a0ax). Anal. Calcd for C37H40O8: C, 72.53; H, 6.58. Found: C, 72.46; H, 6.76.
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyrano-
syl-(1 ! 3)-1,5-anhydro-4,6-O-benzylidene-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (16c). Compound 15c (6.2 mg, 11 mmol) was acetylated and
purified as in the preparation of 14a to give 16c (6.5 mg, 97%) as a syrup:
[a]2D0 –318 (c 0.31, CHCl3); 1H NMR (300 MHz, CDCl3) (inter alia): d 4.29
(ddd, 1H, J1,3 ¼ 2.0 Hz, J2,3 ¼ 3.7 Hz, J3,4 ¼ 7.6 Hz, H-3), 4.21 (dd, 1H,
0
0
J5,6a ¼ 4.6 Hz, J6gem ¼ 11.1 Hz, H-6a), 3.98 (ddd, 1H, J1 ,2 ¼ 2.8 Hz,
J1 ,5a eq ¼ 4.2 Hz, J1 ,5a ax ¼ 11.2 Hz, H-10), 3.92 (dd, 1H, J3 ,4 ¼ J4 ,5 ¼ 9.8 Hz,
H-40), 3.80 (dd, 1H, J3,4 ¼ 7.8 Hz, J4,5 ¼ 11.0 Hz, H-4), 3.51 (dd, 1H,
0
0
0
0
0
0
0
0
J2 ,3 ¼ 2.8 Hz, J3 ,4 ¼ 9.8 Hz, H-30), 1.52 (ddd, 1H, J1 ,5a ax ¼ 11.2 Hz, J5 ,5a ax
¼
0
0
0
0
0
0
0
0
J5a gem ¼ 12.0 Hz, H-5a0ax). Anal. Calcd for C37H40O8: C, 72.53; H, 6.58. Found:
0
C, 72.50; H, 6.66.
1,5-Anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-hex-1-enitol
(5) and 1,5-anhydro-3,4-di-O-benzyl-2-deoxy-5a-carba-D-arabino-hex-
1-enitol (6). To a solution of 3-O-benzyl-4,6-O-benzylidene-2-deoxy-5a-carba-
D-arabino-hex-1-enitol[11] (4, 1.39 g, 4.31 mmol) in THF (56 mL) were added in
turn molecular sieves 4A (3.25 g), a trace of methyl orange, and sodium cyano-
borohydride (3.25 g, 12 molar equiv), and the mixture was stirred for 30 min at
258C. Diethyl ether solution saturated with hydrogen chloride was added to it

Preparation of Building Blocks for Carba-Oligosaccharides
89
until the color turned pink. After stirring continued for 3 h and subsequent treat-
ment with Dowex-50 Wꢀ2 (Hþ) resin, the mixture was filtered through a bed of
Celite. The filtrate was diluted with chloroform (300 mL), and the solution was
washed with saturated aqueous sodium hydrogen carbonate and water, dried
(Na2SO4), and evaporated. The residue was chromatographed on silica gel
(200 g, 1:10 ethyl acetate/hexane, v/v) to give 5 (878 mg, 63%) as crystals and
6 (47 mg, 3%) as a syrup. For further characterization compounds 5 and 6
were converted into the respective acetyl derivatives.
1
5: m.p. 45–48.58C; [a]1D9 –428 (c 1.6, CHCl3); H NMR (300 MHz, CDCl3): d
7.40–7.25 (m, 10 H, 2 ꢀ Ph), 4.74 and 4.68 (ABq, Jgem ¼ 11.7 Hz) and 4.56
and 4.52 (ABq, Jgem ¼ 12.3 Hz) (2 ꢀ CH2Ph), 4.02 (dd, 1H, J1,3 ¼ 2.0 Hz,
J3,4 ¼ 7.6 Hz, H-3), 3.77 (m, 1H, H-4), 3.65 (dd, 1H, J5,6a ¼ 5.5 Hz,
J6gem ¼ 9.2 Hz, H-6a), 3.61 (dd, 1H, J5,6b ¼ 5.0 Hz, J6gem ¼ 9.2 Hz, H-6b), 3.22
(br s, 1H, OH); the 4-O-acetyl derivative: crystals: m.p. 49–508C; [a]2D4 –378
1
(c 0.80, CHCl3); H NMR (300 MHz, CDCl3): d 7.35–7.23 (m, 10 H, 2 ꢀ Ph),
5.79 (dd, 1H, J1,3 ¼ 2.3 Hz, J1,2 ¼ 10.0 Hz, H-1), 5.67 (dd, 1H, J2,3 ¼ 5.0 Hz,
J1,2 ¼ 10.0 Hz, H-2), 5.19 (dd, 1H, J3,4 ¼ 7.3 Hz, J4,5 ¼ 10.5 Hz, H-4), 4.62 and
4.53 (ABq, Jgem ¼ 11.7 Hz), and 4.47–4.40 (ABq, Jgem ¼ 12.0 Hz)
(2 ꢀ CH2Ph), 4.13–4.09 (br ddd, 1H, J1,3 ¼ 2.3 Hz, J2,3 ¼ 5.0 Hz, J3,4
¼
7.3 Hz, H-3), 3.48 (dd, 1H, J5,6a ¼ 4.6 Hz, J6gem ¼ 9.2 Hz, H-6a), 3.38 (dd, 1H,
J5,6b ¼ 6.3 Hz, J6gem ¼ 9.2 Hz, H-6b). Anal. Calcd for C23H26O4: C, 75.38; H,
7.15. Found: C, 75.39; H, 7.21.
1
6: [a]1D9 –218 (c ¼ 1.0, CHCl3); H NMR (300 MHz, CDCl3): d 7.39–7.24 (m, 10
H, 2 ꢀ Ph), 4.98 and 4.74 (ABq, Jgem ¼ 11.2 Hz), and 4.72 and 4.64 (ABq,
Jgem ¼ 11.5 Hz) (2 ꢀ CH2Ph), 4.23 (ddd, 1H, J1,3 ¼ 1.5 Hz, J2,3 ¼ 3.2 Hz,
J3,4 ¼ 7.1 Hz, H-3), 2.62 (br s, 1H, OH); the 6-O-acetyl derivative: [a]1D9 þ3.38
(c 1.0, CHCl3); 1H NMR (300 MHz, CDCl3): d 7.39–7.25 (m, 10H, 2 ꢀ Ph),
4.71 and 4.66 (ABq, Jgem ¼ 11.6 Hz), and 4.91 and 4.63 (ABq, Jgem ¼ 11.0 Hz)
(2 ꢀ CH2Ph), 3.62 (dd, 1H, J3,4 ¼ 7.3 Hz, J4,5 ¼ 10.3 Hz, H-4). Anal. Calcd for
C23H26O4: C, 75.38; H, 7.15. Found: C, 75.28; H, 7.28.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-mannopyranosyl-(1 ! 4)-
1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-hex-1-enitol
(7d). Coupling of 5 (55.3 mg, 170 mmol) and 1 (86.5 mg, 1.5 molar equiv) was
carried out as in the preparation of 7a. The product was purified by chromato-
graphy (silica gel: 27 g, 1:9 ethyl acetate/hexane, v/v) to give 7d [19.7 mg
(17%), 69% based on 4 consumed] as a syrup, along with 4 (40 mg) unchanged:
1
[a]2D4 –228 (c 1.1, CHCl3); H NMR (300 MHz, CDCl3) (inter alia): d 7.47–7.18
(m, 20H, 4 ꢀ Ph), 5.58 (dd, 1H, J1,2 ¼ 10.2 Hz, H-2), 5.54 (s, 1H, CHPh), 4.70
and 4.46 (ABq, Jgem ¼ 12.0 Hz), 4.55 and 4.46 (ABq, Jgem ¼ 11.5 Hz), and
4.46 and 4.37 (ABq, Jgem ¼ 12.2 Hz) (3 ꢀ CH2Ph), 4.13 (dd, 1H,

S. Ogawa and Y. Senba
90
J1 ,2 ¼ 2.7 Hz, J2 ,3 ¼ 2.9 Hz, H-20), 4.05 (m, 1H, J1 ,2 ¼ 2.7 Hz, H-10), 3.76 (dd,
0
0
0
0
0
0
1H, J2 ,3 ¼ 2.9 Hz, J3 ,4 ¼ 9.6 Hz, H-30), 3.41 (dd, 1H, J5,6a ¼ 3.2 Hz,
J6gem ¼ 9.0 Hz, H-6a), 2.35 (br s, 1H, OH).
0
0
0
0
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-a-D-mannopyrano-
syl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (8d). Compound 7d (19 mg, 29 mmol) was acetylated as in the
preparation of 8a to give, after chromatography (silica gel: 2 g, 1:5 ethyl
acetate/hexane, v/v), 8d (21 mg, 99%) as a syrup: [a]2D4 –328 (c 1.05, CHCl3);
1H NMR (300 MHz, CDCl3) (inter alia): d 7.47–7.18 (m, 20H, 4 ꢀ Ph), 5.69
(m, 1H, J1,3 ¼ J1,5a(ax) ¼ ꢀ2.3 Hz, J1,5a(eq) ¼ 4.5 Hz, J1,2 ¼ 10.5 Hz, H-1), 5.57
(br dd, 1H, J ¼ ꢀ3 Hz, H-20), 5.55 (s, 1H, CHPh), 4.62–4.47 (m, 4 H), and
4.44 and 4.36 (ABq, Jgem ¼ 12.2 Hz) (3 ꢀ CH2Ph), 4.01 (br q, 1H, J ¼ ꢀ3 Hz,
H-10), 3.95 (dd, 1H, J5 .6 a ¼ 4.5 Hz, J6 gem ¼ 10.5 Hz, H-60a), 3.87 (dd, 1H,
0
0
0
J2 ,3 ¼ 3.0 Hz, J3 ,4 ¼ 9.8 Hz, H-30), 3.81 (dd, 1H, J4 ,5 ¼ 9.5 Hz, J3 ,4
¼
0
0
0
0
0
0
0
0
9.8 Hz, H-40), 3.63 (dd, 1H, J5 .6 b ¼ 6.9 Hz, J6 gem ¼ 10.5 Hz, H-60b), 3.58 (dd,
1H, J5,6a ¼ 2.4 Hz, J6gem ¼ 9.7 Hz, H-6a), 3.36 (dd, 1H, J5,6b ¼ 2.9 Hz,
0
0
0
0
0
0
0
J6gem ¼ 9.7 Hz, H-6b), 1.88 (m, 1H, H-5), 1.54 (ddd, 1H, J1 ,5a eq ¼ J5 ,5a eq
¼
¼
1.0 Hz, J5a gem ¼ 13.5 Hz, H-5a0eq), 1.16 (ddd, 1H, J1 ,5a ax ¼ 2.7 Hz, J5 ,5a ax
0
0
0
0
0
J5a gem ¼ 13.5 Hz, H-5a0ax). Anal. Calcd for C44H48O8: C, 74.98; H, 6.86.
0
Found: C, 75.09; H, 6.96.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-a-D-arabino-hex-2-ulopyrano-
syl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (9d). Compound 7d (20.7 mg, 31.2 mmol) was treated with acetic
anhydride (89 mL, 30 molar equiv) in DMSO (0.60 mL) as in the preparation of
9a to give, after chromatography (silica gel: 4 g, 1:15 ethyl acetate/toluene,
v/v), 9d (18.7 mg, 91%) as a syrup: [a]2D7 –518 (c 0.80, CHCl3); 1H NMR
(300 MHz, CDCl3) (inter alia): d 7.55–7.21 (m, 20H, 4 ꢀ Ph), 5.56 (s, 1H,
CHPh), 5.49 (br d, 1H, J1,2 ¼ 10.0 Hz, H-2), 4.84 and 4.51 (ABq,
Jgem ¼ 10.3 Hz), 4.64 and 4.42 (ABq, Jgem ¼ 12.3 Hz), and 4.54–4.40 (m, 2 H)
(3 ꢀ CH2Ph), 4.21 (dd, 1H, J1 ,5a ax ¼ 2.5 Hz, J1 ,5a eq ¼ 3.2 Hz, H-10), 4.06
(ddd, 1H, J1,3 ¼ 2.0 Hz, J2,3 ¼ 2.2 Hz, J3,4 ¼ 7.1 Hz, H-3), 3.43 (dd, 1H,
0
0
0
0
0
0
J5,6a ¼ 3.2 Hz, J6gem ¼ 10.9 Hz, H-6a), 1.80 (ddd, 1H, J1 ,5a eq ¼ 3.2 Hz,
J5 ,5a eq ¼ 3.4 Hz, J5a gem ¼ 14.3 Hz, H-5a0eq), 1.11 (ddd, 1H, J1 ,5a ax ¼ 2.5 Hz,
0
0
0
0
0
J5 ,5a ax ¼ 11.7 Hz, J5a gem ¼ 14.3 Hz, H-5a0ax). Anal. Calcd for C42H44O7: C,
0
0
0
76.34; H, 6.71. Found: C, 76.28; H, 6.91.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-arabino-hex-2-ulopyrano-
syl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (10d). Compound 9c (15.7 mg, 23.8 mmol) was treated with DBU
(5.3 mL, 1.5 molar equiv) in toluene (0.60 mL) for 6 h at 658C as in the preparation
of 10a. After the usual processing, the products were chromatographed on silica

Preparation of Building Blocks for Carba-Oligosaccharides
91
gel (3 g, 1:30 ethyl acetate/toluene, v/v) to give 9d (5.7 mg, 36%) and 10d (7.3 mg,
47%) as crystals: mp 138–1398C; [a]2D5 –298 (c 0.37, CHCl3); 1H NMR (300MHz,
CDCl3) (inter alia):
d
7.51–7.20 (m, 20H, 4 ꢀ Ph), 5.77 (m, 1H,
J1,3 ¼ J1,5a(ax) ¼ ꢀ2 Hz, J1,5a(eq) ¼ 4.2 Hz, J1,2 ¼ 9.5 Hz, H-1), 5.69 (br dd, 1H,
J1,3 ¼ 1.9 Hz, J1,2 ¼ 10.1 Hz, H-2), 5.48 (s, 1H, CHPh), 4.80 and 4.53 (ABq,
Jgem ¼ 12.2 Hz), and 4.70 and 4.43 (ABq, Jgem ¼ 11.4 Hz) (2 ꢀ CH2Ph), 4.14 (br
d, 1H, J3,4 ¼ 7.6 Hz, H-3), 3.73 (dd, 1H, J5,6a ¼ 2.7 Hz, J6gem ¼ 9.2 Hz, H-6a),
1.08 (ddd, 1H, J1 ,5a ax ¼ 12.6 Hz, J5 ,5a ax ¼ J5a gem ¼ 12.7 Hz, H-5a0ax).
0
0
0
0
0
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-a-D-glucopyranos-
yl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-hex
-1-enitol (12d). A solution of 10d (22 mg, 33 mmol) in THF (1.0 mL) was treated
with NaBH4 (3.7 mg, 3 molar equiv) for 3 h at 08C. After the reaction was
quenched by addition of water, the mixture was evaporated to dryness, and
the residual product was acetylated in the usual manner. The product was
chromatographed by a preparative TLC (1:3 EtOAc/toluene irrigated three
times) to give 12d (12 mg, 53%) and 8d (7 mg, 31%): [a]2D1 –58 (c 0.6, CHCl3);
1H NMR (300 MHz, CDCl3) (inter alia): d 7.54–7.26 (m, 20H, 4 ꢀ Ph), 5.66
(br d, 1H, J1,2 ¼ 10.0 Hz, H-2), 5.59 (s, 1H, CHPh), 4.89 (dd, 1H,
J1 ,2 ¼ 3.6 Hz, J2 ,3 ¼ 9.8 Hz, H-20), 4.53 (m, 1H, H-10), 4.93 and 4.67 (ABq,
Jgem ¼ 11.7 Hz), 4.61 and 4.47 (ABq, Jgem ¼ 11.5 Hz), and 4.58 and 4.45 (ABq,
Jgem ¼ 12.2 Hz) (3 ꢀ CH2Ph), 2.09 (dddd, 1H, J5,6b ¼ 3.6 Hz, J5,6a ¼ 3.7 Hz,
J5,5a(eq) ¼ 4.6 Hz, J4,5 ¼ 9.0 Hz, H-5), 2.02 (s, 3H, Ac), 1.83 (ddd, 1H,
0
0
0
0
J1 ,5a eq ¼ 2.9 Hz, J5 ,5a eq ¼ 3.7 Hz, J5a gem ¼ 14.4 Hz, H-5a0eq), 1.00 (ddd, 1H,
0
0
0
0
0
J1 ,5a ax ¼ 1.6 Hz, J5 ,5a ax ¼ 12.9 Hz, J5a gem ¼ 14.4 Hz, H-5a0ax). Anal. Calcd
0
0
0
0
0
for C44H48O8: C, 74.98; H, 6.86. Found: C, 74.82; H, 7.01.
3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-glucopyranosyl-(1 ! 4)-1,
5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-hex-1-enitol
(13d) and 3-O-Benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyrano-
syl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (15d). Compound 10d (10.0 mg, 15mmol) was treated with NaBH4
in the presence of cerium(III) chloride in methanol as in the preparation of 13a
and 15a. The products were chromatographed on silica gel (2 g, 1:25 ethyl
acetate/toluene, v/v) to give 13d (4.5mg, 47%) and 15d (3.6 mg, 38%) as crystals.
1
13d: mp 140–1428C; [a]2D7 –518 (c 0.23, CHCl3); H NMR (300 MHz, CDCl3)
(inter alia): d 7.50–7.24 (m, 20H, 4 ꢀ Ph), 5.50 (s, 1H, CHPh), 4.92 and 4.80
(ABq, Jgem ¼ 11.5 Hz), 4.75 and 4.45 (ABq, Jgem ¼ 11.5 Hz), and 4.62 and 4.49
(ABq, Jgem ¼ 12.2 Hz) (3 ꢀ CH2Ph), 4.16 (br s, 1H, OH), 3.73 (ddd, 1H,
J1 ,5a eq ¼ 4.6 Hz, J1 ,2 ¼ 8.8 Hz, J1 ,5a ax ¼ 11.2 Hz, H-10), 2.33 [dd, 1H,
J5agem ¼ 11.2 Hz, J5,5a(ax) ¼ 11.4 Hz, H-5a(ax)], 2.11 [dd, 1H, J5,5a(eq) ¼ 4.0 Hz,
J5agem ¼ 11.2 Hz, H-5a(eq)], 1.96 (m, 1H, H-5), 1.71 (ddd, 1H,
0
0
0
0
0
0

S. Ogawa and Y. Senba
92
J5 ,5a eq ¼ 3.2 Hz, J1 ,5a eq ¼ 4.6 Hz, J5a gem ¼ 12.9 Hz, H-5a0eq), 1.54 (m, 1H,
0
0
0
0
0
H-50), 0.91 (ddd, 1H, J1 ,5a ax ¼ 11.2 Hz, J5 ,5a ax ¼ J5a gem ¼ 12.9 Hz, H-5a0ax).
0
0
0
0
0
1
15d: mp 105.5–1088C; [a]2D6 –108 (c 0.69, CHCl3); H NMR (300 MHz, CDCl3)
(inter alia):
d
7.51–7.21 (m, 20H, 4 ꢀ Ph), 5.76 (m, 1H, J1,3 ¼
J1,5a(ax) ¼ ꢀ2.2 Hz, J1,5a(eq) ¼ 4.5 Hz, J1,2 ¼ 10.0 Hz, H-1), 5.70 (m, 1H,
J2,3 ¼ J2,5a(eq) ¼ ꢀ1.5 Hz, J1,2 ¼ 10.0 Hz, H-2), 5.57 (s, 1H, CHPh), 4.61 and
4.54 (ABq, Jgem ¼ 11.2 Hz), 4.70 and 4.49 (ABq, Jgem ¼ 12.2 Hz), and 4.68–
4.44 (m, 2 H) (3 ꢀ CH2Ph), 4.32 (dd, 1H, J1 ,2 ¼ 2.4 Hz, J2 ,3 ¼ 2.7 Hz, H-20),
4.12 (ddd, 1H, J2,3 ¼ ꢀ1.5 Hz, J1,3 ¼ 1.7 Hz, J3,4 ¼ 7.6 Hz, H-3), 3.44 (dd, 1H,
0
0
0
0
0
0
0
0
J5,6a ¼ 2.9 Hz, J6gem ¼ 9.3 Hz, H-6a), 3.33 (dd, 1H, J2 ,3 ¼ 2.7 Hz, J3 ,4
¼
9.5 Hz, H-30), 2.85 (br s, 1H, OH).
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-glucopyrano-
syl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (14d). Compound 13d (19.3 mg, 29 mmol) was acetylated conven-
tionally to give, after chromatography (silica gel: 2 g, 1:12 ethyl acetate/
1
toluene, v/v), 14d (19.5 mg, 95%) as a syrup: [a]2D6 –148 (c 0.95, CHCl3); H
NMR (300 MHz, CDCl3) (inter alia): d ¼ 7.49–7.22 (m, 20H, 4 ꢀPh), 5.75 (br
d, 1H, J1,2 ¼ 10.3 Hz, H-1), 5.67 (br d, 1H, J1,2 ¼ 10.3 Hz, H-2), 5.50 (s, 1H,
CHPh), 5.02 (dd, 1H, J1 ,2 ¼ J2 ,3 ¼ 9.4 Hz, H-20), 4.89 and 4.61 (ABq,
Jgem ¼ 11.7 Hz), 4.71 and 4.51 (ABq, Jgem ¼ 11.5 Hz), and 4.51 and 4.44 (ABq,
Jgem ¼ 12.0 Hz) (3 ꢀ CH2Ph), 3.68–3.56 (m, 1H, H-10), 1.92 (s, 3H, Ac), 1.51
0
0
0
0
(m, 1H, H-50), 0.92 (ddd, 1H, J5 ,5a ax ¼ 11.5 Hz, J1 ,5a ax ¼ 12.9 Hz,
0
0
0
0
J5a gem ¼ 13.2 Hz, H-5a0ax). Anal. Calcd for C44H48O8: C, 74.98; H, 6.86.
0
Found: C, 74.83; H, 6.90.
2-O-Acetyl-3-O-benzyl-4,6-O-benzylidene-5a-carba-b-D-mannopyrano-
syl-(1 ! 4)-1,5-anhydro-3,6-di-O-benzyl-2-deoxy-5a-carba-D-arabino-
hex-1-enitol (16d). Compound 15d (10.8 mg, 16 mmol) was acetylated conven-
tionally to give, after chromatography (silica gel: 2 g, 1 : 10 ethyl acetate/
toluene, v/v), 16d (11 mg, 96%) as a syrup: [a]2D7 –288 (c 0.37, CHCl3); 1H
NMR (300 MHz, CDCl3) (inter alia): d 7.50–7.22 (m, 20H, 4 ꢀ Ph), 5.54
(s, 1H, CHPh), 4.73 and 4.47 (ABq, Jgem ¼ 11.4 Hz), 4.62 and 4.42 (ABq,
Jgem ¼ 12.5 Hz), and 4.61 and 4.49 (ABq, Jgem ¼ 12.1 Hz) (3 ꢀ CH2Ph), 4.07
(br dd, 1H, J1,3 ¼ 2.2 Hz, J3,4 ¼ 7.6 Hz, H-3), 3.81–3.73 (m, 1H, H-10), 3.33
(dd, 1H, J2 ,3 ¼ 2.8 Hz, J3 ,4 ¼ 9.8 Hz, H-30), 2.12 (s, 3H, Ac). Anal. Calcd for
0
0
0
0
C44H48O8: C, 74.98; H, 6.86. Found: C, 74.73; H, 7.07.
ACKNOWLEDGEMENTS
The authors would like to thank Ms. Lili Zhao for elementary analyses and
Ms. Miki Kanto for her enthusiastic assistance in preparing this manuscript.

Preparation of Building Blocks for Carba-Oligosaccharides
93
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